Air raids

The development comes two days after the Chadian government confirmed that the country's air force had carried out cross-border air raids against opposition fighters which it accuses Khartoum of backing.

Seven contingents of opposition fighters were destroyed by last week's air attacks, while ground forces captured 100 prisoners on the border, Chad said.

Khartoum has denied that Chadian opposition fighters were gathering inside Chad and on Tuesday it called on Ndjamena to call off its plan to launch military raids inside Sudan.

"We would urge Chad to refrain from violating the sovereignty of the country and stop its aggression," Ali Youssef Ahmed, an official in Sudan's foreign ministry, told Reuters news agency.

"Chad needs to come to its senses and respect the [peace] agreement which was signed in Doha [the Qatari capital]. We hold them responsible for any repercussions that may arise from such actions."

Khartoum and Ndjamena last month agreed to stop using force against each other.

But Chad alleged that Sudan had helped send armed opposition groups into Chadian territory within hours of the peace deal being reached.

Ahmed on Tuesday denied Chad’s accusation, saying the Chadian opposition fighters had received no help from Sudan and that they had launched their attack from inside Chad before the peace deal was agreed.