Rebels in Darfur have splintered into a confusing array of rival factions
Sudan's military has admitted carrying out a wave of bombings in the Darfur region on Tuesday.
An army spokesman said they had targeted rebels who had failed to back the ceasefire announced in November.
The BBC's Sudan correspondent says it is highly unusual for the military to admit aerial attacks in Darfur.
It comes amid renewed tension over whether the International Criminal Court will charge Sudan President Omar al-Bashir for war crimes in Darfur.
Sudan's government has always rejected charges that it armed the Janjaweed militias accused of widespread atrocities against civilians in the region.
A commander from the rebel Justice and Equality Movement (Jem) confirmed that government planes carried out the attack, around the southern Darfuri town of Muhajiriya.
In a statement, a military spokesman said the army had bombed the area to protect civilians living there.
Senior government officials say they have intelligence to suggest that Jem will launch a series of attacks ahead of an International Criminal Court (ICC) ruling, the BBC's Amber Henshaw in Khartoum reports.
Judges at the ICC in The Hague are expected to make a decision about issuing an arrest warrant for Mr Bashir by the end of the month.
The government has warned an arrest warrant could lead to an escalation of the Darfur conflict because it may embolden rebel groups in the region.
On Tuesday, Hillary Clinton - who is to become the next US secretary of state after Barack Obama is inaugurated as president next week - said the US was considering creating no-fly zones over Darfur.
The UN estimates that up to 2.7 million people have been forced from their homes in Darfur and some 300,000 have died during nearly six years of conflict.
So far only half of the 26,000 troops authorised for the joint United Nations and African Union peace force have been sent to the remote region, the size of France.
A chronology of key events:
1881 - Revolt against the Turco-Egyptian administration.
1899-1955 Sudan is under joint British-Egyptian rule.
1956 - Sudan becomes independent.
1958 - General Abbud leads military coup against the civilian government elected earlier in the year
1962 - Civil war begins in the south, led by the Anya Nya movement.
1964 - The "October Revolution" overthrows Abbud and a national government is established
1969 - Jafar Numayri leads the "May Revolution" military coup.
1971 - Sudanese Communist Party leaders executed after short-lived coup against Numayri
1972 - Under the Addis Ababa peace agreement between the government and the Anya Nya the south becomes a self-governing region.
1978 - Oil discovered in Bentiu in southern Sudan.
1983 - Civil war breaks out again in the south involving government forces and the Sudan People's Liberation Movement (SPLM), led by John Garang.
Islamic law imposed
1983 - President Numayri declares the introduction of Sharia (Islamic law).
- After widespread popular unrest Numayri is deposed by a group of officers and a Transitional Military Council is set up to rule the country.
1986 - Coalition government formed after general elections, with Sadiq al-Mahdi as prime minister.
1988 - Coalition partner the Democratic Unionist Party drafts cease-fire agreement with the SPLM, but it is not implemented.
1989 - National Salvation Revolution takes over in military coup.
1993 - Revolution Command Council dissolved after Omar al-Bashir is appointed president.
1995 - Egyptian President Mubarak accuses Sudan of being involved in attempt to assassinate him in Addis Ababa.
1998 - US launches missile attack on a pharmaceutical plant in Khartoum, alleging that it was making materials for chemical weapons.
1998 - New constitution endorsed by over 96% of voters in referendum.
1999 - President Bashir dissolves the National Assembly and declares a state of emergency following a power struggle with parliamentary speaker, Hassan al-Turabi.
Advent of oil
1999 - Sudan begins to export oil.
2000 President Bashir meets leaders of opposition National Democratic Alliance for first time in Eritrea.
Main opposition parties boycott presidential elections. Incumbent Bashir is re-elected for further five years.
A US missile targeted a Khartoum pharmaceutical plant in 1998
2001 Islamist leader Hassan al-Turabi's party, the Popular National Congress, signs memorandum of understanding with the southern rebel SPLM's armed wing, the Sudan People's Liberation Army (SPLA). Al-Turabi is arrested the next day, with more arrests of PNC members in the following months.
Government accepts Libyan/Egyptian initiative to end the civil war after failure of peace talks between President Bashir and SPLM leader John Garang in Nairobi.
US extends unilateral sanctions against Sudan for another year, citing its record on terrorism and rights violations.
2002 - Government and SPLA sign landmark ceasefire agreement providing for six-month renewable ceasefire in central Nuba Mountains - a key rebel stronghold.
Talks in Kenya lead to a breakthrough agreement between the government and southern rebels on ending the 19-year civil war. The Machakos Protocol provides for the south to seek self-determination after six years.
2003 February - Rebels in western region of Darfur rise up against government, claiming the region is being neglected by Khartoum.
2003 October - PNC leader Turabi released after nearly three years in detention and ban on his party is lifted.
Uprising in west
2004 January - Army moves to quell rebel uprising in western region of Darfur; hundreds of thousands of refugees flee to neighbouring Chad.
2004 March - UN official says pro-government Arab "Janjaweed" militias are carrying out systematic killings of African villagers in Darfur.
Army officers and opposition politicians, including Islamist leader Hassan al-Turabi, are detained over an alleged coup plot.
2004 May - Government and southern rebels agree on power-sharing protocols as part of a peace deal to end their long-running conflict. The deal follows earlier breakthroughs on the division of oil and non-oil wealth.
2004 September - UN says Sudan has not met targets for disarming pro-government Darfur militias and must accept outside help to protect civilians. US Secretary of State Colin Powell describes Darfur killings as genocide.
2005 January - Government and southern rebels sign a peace deal. The agreement includes a permanent ceasefire and accords on wealth and power sharing.
UN report accuses the government and militias of systematic abuses in Darfur, but stops short of calling the violence genocide.
2005 March - UN Security Council authorises sanctions against those who violate ceasefire in Darfur. Council also votes to refer those accused of war crimes in Darfur to International Criminal Court.
2005 June - Government and exiled opposition grouping - National Democratic Alliance (NDA) - sign reconciliation deal allowing NDA into power-sharing administration.
President Bashir frees Islamist leader Hassan al-Turabi, detained since March 2004 over alleged coup plot.
2005 9 July - Former southern rebel leader John Garang is sworn in as first vice president. A constitution which gives a large degree of autonomy to the south is signed.
2005 1 August - Vice president and former rebel leader John Garang is killed in a plane crash. He is succeeded by Salva Kiir. Garang's death sparks deadly clashes in the capital between southern Sudanese and northern Arabs.
2005 September - Power-sharing government is formed in Khartoum.
2005 October - Autonomous government is formed in the south, in line with January 2005 peace deal. The administration is dominated by former rebels.
2006 May - Khartoum government and the main rebel faction in Darfur, the Sudan Liberation Movement, sign a peace accord. Two smaller rebel groups reject the deal. Fighting continues.
2006 August - Sudan rejects a UN resolution calling for a UN peacekeeping force in Darfur, saying it would compromise sovereignty.
2006 October - Jan Pronk, the UN's top official in Sudan, is expelled.
2006 November - African Union extends mandate of its peacekeeping force in Darfur for six months.
Hundreds are thought to have died in the heaviest fighting between northern Sudanese forces and their former southern rebel foes since they signed a peace deal last year. Fighting is centred on the southern town of Malakal.
2007 April - Sudan says it will accept a partial UN troop deployment to reinforce African Union peacekeepers in Darfur, but not a full 20,000-strong force.
War crimes charges
2007 May - International Criminal Court issues arrest warrants for a minister and a janjaweed militia leader suspected of Darfur war crimes.
US President George W Bush announces fresh sanctions against Sudan.
2007 July - UN Security Council approves a resolution authorising a 26,000-strong force for Darfur. Sudan says it will co-operate with the United Nations-African Union Mission in Darfur (Unamid).
2007 October - SPLM temporarily suspends participation in national unity government, accusing Khartoum of failing to honour the 2005 peace deal.
2007 December - SPLM resumes participation in national unity government.
2008 January - UN takes over Darfur peace force.
Within days Sudan apologises after its troops fire on a convoy of Unamid, the UN-African Union hybrid mission.
Government planes bomb rebel positions in West Darfur, turning some areas into no-go zones for aid workers.
2008 February - Commander of the UN-African Union peacekeepers in Darfur, Balla Keita, says more troops needed urgently in west Darfur.
2008 March - Russia says it's prepared to provide some of the helicopters urgently needed by UN-African Union peacekeepers.
Tensions rise over clashes between an Arab militia and SPLM in Abyei area on north-south divide - a key sticking point in 2005 peace accord.
Presidents of Sudan and Chad sign accord aimed at halting five years of hostilities between their countries.
2008 April - Counting begins in national census which is seen as a vital step towards holding democratic elections after the landmark 2005 north-south peace deal.
UN humanitarian chief John Holmes says 300,000 people may have died in the five-year Darfur conflict.
2008 May - Southern defence minister Dominic Dim Deng is killed in a plane crash in the south.
Tension increases between Sudan and Chad after Darfur rebel group mounts raid on Omdurman, Khartoum's twin city across the Nile. Sudan accuses Chad of involvement and breaks off diplomatic relations.
Intense fighting breaks out between northern and southern forces in disputed oil-rich town of Abyei.
2008 June - President Bashir and southern leader Salva Kiir agree to seek international arbitration to resolve dispute over Abyei.
2008 July - The International Criminal Court's top prosecutor calls for the arrest of President Bashir for genocide, crimes against humanity and war crimes in Darfur; the appeal is the first ever request to the ICC for the arrest of a sitting head of state. Sudan rejects the indictment.
2008 September - Darfur rebels accuse government forces backed by militias of launching air and ground attacks on two towns in the region.
2008 October - Allegations that Ukrainian tanks hijacked off the coast of Somalia were bound for southern Sudan spark fears of an arms race between the North and former rebels in the South.
2008 November - President Bashir announces an immediate ceasefire in Darfur, but the region's two main rebel groups reject the move, saying they will fight on until the government agrees to share power and wealth in the region.
2008 December - The Sudanese army says it has sent more troops to the sensitive oil-rich South Kordofan state, claiming that a Darfur rebel group plans to attack the area.