Chad has blamed rebels groups in Sudan's Darfur region for the breakdown in talks with the Sudan government.
Sudan says that Jem is linked to the Islamist opposition
Chad hosts some 200,000 refugees from Darfur and has been mediating in talks between the two sides.
Chad's foreign minister told the BBC that the leadership of one of the rebel groups was badly divided, making serious negotiations difficult.
This statement is likely to please the Sudan government, which is itself under strong pressure to stop the fighting.
A United Nations' resolution threatens to impose sanctions on Sudan's oil industry unless the government reins in the Arab Janjaweed militias, blamed for the worst atrocities in Darfur.
More than a million people have fled their homes, in what the US and human rights groups have called a genocide against Darfur's non-Arab groups.
Divide and rule
On Tuesday, Sudan's government said it would no longer negotiate with the Justice and Equality Movement (Jem) because it was linked to a coup plot.
Deputy Foreign Minister Najeib Abdel Wahab said Jem was allied to Sudan opposition Islamist leader Hassan al-Turabi, in prison in connection with the alleged plot.
Chad's Foreign Minister Nagoum Yamassoum also blamed Jem for the breakdown in the peace talks.
But Mr Wahab said Sudan was prepared to continue talks with the second rebel group, the Sudan Liberation Army.
Talks between both rebel groups and the government in Nigeria have been suspended for a month.
The rebels want the Janjaweed to disarm first but Sudan insists that all three groups should lay down their weapons at the same time.
Sudan argues that the threat of sanctions against the government is encouraging the rebels not to reach an agreement in talks.
The BBC's Mark Doyle in Sudan says critics of the Sudanese military government may say that distinguishing between the two groups is a classic example of the divide-and-rule policies that have kept it in power for many years.
Some 10,000 people are dying from disease and malnutrition in Darfur's refugee camps each month but aid agencies say that access is improving and they are able to deliver more food.