Sudan has said it is prepared to halt military operations in the Darfur region if rebels withdraw from some positions they captured earlier this year.
A government negotiator said Sudan would stop fighting if rebels withdrew from positions captured after the signing of a roundly ignored April ceasefire.
The Sudanese offer was in line with a compromise deal pushed by African Union mediators hosting the talks, Sudan said.
"But the question is whether the rebels will withdraw or stop all violations of the cease-fire," the negotiator said.
Rebel delegates were not available for comment.
Three earlier rounds of peace talks have not calmed Darfur, which the United Nations calls the world's worst humanitarian crisis.