Sudan's government and the Justice and Equality Movement (Jem), Darfur's most active rebel group, have agreed to sign a declaration of good intentions on Tuesday, Sheikh Hamad bin Jassem al-Thani, Qatar's prime minister, has said.
"There has been great progress ... and we now have an agreement that may be signed," Sheikh Hamad told reporters on Monday.
Qatar has been mediating peace talks between Khartoum and the Jem since last Tuesday.
"The content of the agreement, which will be signed tomorrow, has the agreement of all parties," the prime minister said in reference to all participants of the talks in Doha, the Qatari capital.
Qatar, the United Nations, the African Union and the Arab League have all sponsored the negotiations, stressing that the Doha talks are preliminary and intended to pave the way for a broader peace conference on Darfur.
The rebel group is reported to have agreed to a prisoner swap with the Sudanese government.
"The two sides have committed themselves in principle to an exchange of prisoners, to be freed in successive groups between now and the launch of talks on a framework agreement on peace in Darfur," Tahar el-Fakih, a Jem delegation member, told AFP news agency.
Amin Hassan Omar, a member of the Sudanese government delegation, was quoted by the Qatar News Agency as confirming that "on the principle ... there is a commitment to release prisoners and detainees for events linked to the Darfur conflict".
Monday's development followed a long meeting between the heads of the two delegations, Khalil Ibrahim, leader of Jem, and Nafie Ali Nafie, an aide to Omar al-Bashir, the Sudanese president.
According to the United Nations, 300,000 people have died and more than 2.2 million have fled their homes since rebels in the western region rose up against the Khartoum government in February 2003.
Sudan, however, puts the death toll at only 10,000.