The African Union has given the Sudanese government and Darfur rebels 24 hours to end fighting in the vast desert region.
It says after that time it will report any cease-fire violations to the United Nations Security Council.
The pan-African body issued the warning Friday in Abuja, Nigeria, where mediators and representatives from both sides are gathered for peace talks. The negotiations have stalled amid allegations of renewed fighting.
Earlier Friday, the commander of the African Union's observer force in Darfur, Nigerian General Festus Okonkwo, briefed mediators on the situation, saying the Sudanese government appears to be preparing a major military offensive in the region.
He also detailed truce violations by the government and rebels in Darfur and said a huge amount of weapons have poured into the region over the last two weeks.
Some information provided by AP and Reuters.