"They signed a humanitarian ceasefire in N'Djamena last night for the opening up of aid corridors so that aid can be distributed to those in need," said State Minister for Foreign Affairs Najib al-Khair Abd al-Wahab.
Peace talks in the Chadian capital N'Djamena are continuing with two rebel groups who launched a revolt in February last year accusing the Khartoum government of arming Arab militias to loot and burn African villages.
Wahab said the ceasefire would take immediate effect.
"This will be ongoing while the two sides seek to find a political resolution to the conflict," he added.
On Wednesday UN chief Kofi Annan warned a Rwanda-style genocide may be in the making in arid Darfur and said international military forces could be needed - a suggestion at once rejected by the Khartoum government.
Two senior UN officials have described the killing and looting in Darfur as a "scorched earth" campaign and "ethnic cleansing". Both said Khartoum had done nothing to stop the bloodshed.
The United Nations estimates more than one million people have been affected by the conflict. Some 110,000 refugees have fled into neighbouring Chad.