A deadline for the two remaining rebel groups in Sudan's Darfur region to sign up to a peace agreement has expired.
SLA faction leader Abdel Wahid Nur refused to sign earlier in May
The Justice and Equality Movement and a faction of the Sudan Liberation Army rejected the deal, initial reports say.
African Union mediators had been trying to persuade them to sign the 5 May deal before 2100 GMT on Wednesday.
The two groups have demanded changes to the text of the agreement aimed at ending the conflict, in which at least 200,000 people have died.
Threee years of fighting has forced some two million people from their homes, in what aid agencies say is one of the world's worst humanitarian crises.
Only the main faction of the Sudan Liberation Army signed the AU-brokered deal with the government in the Sudanese capital, Khartoum.
Last-minute talks with the two groups have been continuing both in Khartoum and in Slovenia, where its president is leading negotiations.
AU spokesman Noureddine Mezni told AFP news agency that AU commission chief Alpha Oumar Konare Konare would "indicate the next steps to be taken" on Thursday.
The AU has warned that the rebels refusing to sign the agreement could face sanctions and that it will urge the UN Security Council to do the same.
The two rebel groups say the current deal is unjust and are asking for:
- More political posts in a proposed transitional government
- A say in the disarmament of pro-government militias
- Compensation for victims of the conflict.
The rebels took up arms in February 2003, accusing the government of discriminating against Darfur's black Africans in favour of Arabs.
The Sudanese army and the pro-government Janjaweed militia then began attacking civilians in Darfur, driving people from their homes and attacking refugee camps.
A lack of money and insecurity means aid workers cannot reach parts of the region.
Sudan denies arming the Arab militias and says the problems have been exaggerated.