Chadian rebels on Friday dismissed the latest peace pact signed between Chad and Sudan and vowed to pursue their campaign to overthrow President Idriss Deby unless he agreed to a dialogue.

Chadian President Deby and his Sudanese counterpart Omar Hassan al-Bashir signed a peace agreement in Senegal late on Thursday meant to end cross-border rebel attacks in a region which includes Sudan's war-torn Darfur.

The deal, witnessed by U.N. Secretary-General Ban Ki-moon, and representatives of the European Union and the African Union, aims to revive a string of past pacts that have failed to end fighting on both sides of the Chad-Sudan border.

"It doesn't concern us," Ali Gadaye, spokesman for the Chadian rebel National Alliance, told Reuters.

"If Deby doesn't want dialogue, then we're going to chase him out by force," he added. The National Alliance was part of a rebel coalition that attacked the Chadian capital N'Djamena last month, besieging Deby in his presidential palace for two days.

In Thursday's accord, brokered by Senegalese President Abdoulaye Wade, Deby and Bashir pledged to ban the activities of all armed groups and to prevent the use of their respective territories to destabilise their neighbours.

Gadaye shrugged this off.

"We're in our own national territory and we have a clear objective: to liberate our people who are being held hostage by a family clan (Deby)," he said, speaking via a satellite phone.

Foreign diplomats say Chadian rebels have regularly used the Darfur frontier region as a base from which to launch incursions into Chad. Sudan has in turn repeatedly accused Chad's government of backing Darfuri rebel groups.