NDJAMENA, April 1, 2008 (AFP) - Fighting broke out between rebel and government forces in eastern Chad on Tuesday, nearly two months after a failed bid to oust President Idriss Deby Itno, rebels and the government said.

The clashes erupted around Ade town in hot, arid eastern territory bordering Sudan's Darfur region, said Ali Gadaye, spokesman for the main rebel group, the National Alliance (AN), led by General Mahamat Nouri.

A statement from Chad's defence ministry confirmed the fighting and claimed that the rebel attack was by Sudan in violation of the March 13 peace pact made in Dakar, the latest of many signed between the two neighbours.

The statement described the rebels as 'mercenaries' and said 'government forces pushed back the enemy, which is completely routed.'

Gadaye, reached by satellite telephone from Libreville denied this, and each side blamed the other for the clashes.

'There is fighting near Ade and it is still taking place,' Gadaye said.

'Government forces came, they attacked us, we attacked them back and we are now occupying Ade,' said a second rebel spokesman who asked not to be named and said the town was still in rebel hands at 10:00 am (0900 GMT).

An alliance of three rebel groups crossed the whole of southern Chad from the Sudan border area early this year and launched an assault on Ndjamena over the weekend of February 2-3.

They were driven out by Deby's troops with French military intelligence and reconnaissance support, after the head of state was holed up in his palace and an estimated 400 people were killed and thousands fled across the border.

The rebels then withdrew to the southeast of Chad, their fractious alliance fell apart on tribal lines and reformed, headed by Nouri, who was last weekend joined by the Union of Forces for Change and Democracy (UFCD).

Ade lies 150 kilometres (95 miles) southeast of Abeche, the main town in east Chad, where the army and French troops permanently deployed in the former colony are based, along with a contingent in Ndjamena.

Abeche is also being turned into the headquarters of a 3,700-strong force called EUFOR Chad-CAR, in which peacekeeping troops from 14 European nations are currently deploying with a year-long UN mandate to protect Darfur refugees in Chad and the Central African Republic to the south.

EUFOR troops, commanded by an Irish general at a headquarters near Paris and a French one on the ground in Chad, are also mandated to protect local people in both Chad and the CAR displaced by insurgency and to ensure that relief workers can provide aid unhindered.

The rebel offensive on Ndjamena early in February delayed EUFOR deployment, but these soldiers are due to be on the ground by the start of May's rainy season and have no mandate to intervene in internal conflict unless attacked.

The National Alliance rebel movement emerged as such three weeks after the assault on Ndjamena. Nouri is a former defence minister from the Gorane ethnic group, who fell out with Deby.

Deby and Sudan's President Omar al-Beshir last month signed the sixth pact between the two countries on the sidelines of a summit of the Organisation of the Islamic Conference in Senegal, where they again agreed to prevent rebels from operating out of their territory and to drop support.

All previous such accords have been breached.

Chad on Tuesday urged mediators in the Dakar accord -- Senegal, Gabon, Congo and Libya -- to 'assume their responsibilities to end this aggression with its unforseeable consequences.'