A state of emergency, announced earlier, also took effect on Tuesday to curb ethnic violence that has killed hundreds of people and forced several thousands from their homes in the southeast.

Besides, censorship has been imposed on the press and other local radio stations under the state of emergency already declared, Al Jazeera said.

Chadian authorities have, however, denied any military build-up along its border with Sudan, contradicting a statement made by the North Darfur governor to Al Jazeera.

Speaking to Al Jazeera on Monday, the governor said Chad had amassed government forces, in addition to rebels from the Sudanese National Salvation Front, along the Sudan-Chad border.

Chad shares with Sudan a warrior tradition and a history of violent clan warfare where the bearing of arms is common.

The new measures gave regional governors wide-ranging powers to ensure security, including a ban on unauthorised firearms.

Pascal Yoadimnadji, the prime minister, said in an address to the nation on Tuesday: "Those illegally holding weapons of war, whoever they are, must immediately hand them over to the authorities. Those refusing will risk exemplary punishment."

Violence spillover

The UN refugee agency UNHCR said the inter-communal clashes risked getting out of control, and it appealed for an international protection force to be deployed.

"UNHCR urges the international community to quickly mobilise a multi-dimensional presence in Chad to help protect hundreds of thousands of Chadian civilians and Sudanese refugees, as well as aid workers trying to help them," it said.

President Idriss Deby's government, already facing an armed insurgency he accuses neighbouring Sudan of backing, says repeated cross-border raids by Sudanese Arab militias known as Janjawid are turning Chad's Arab and non-Arab communities against each other.

Khartoum denies promoting the violence.

'Towns burnt'

Yoadimnadji said: "These inter-communal clashes, whose victims run into the hundreds, exceed all proportions and throw into peril national cohesion ... Entire towns have been burnt and livestock decimated."

UNHCR said:

Non-Arab tribes have been at
the receiving end of the attacks

"We fear the inter-communal hostilities are spiralling out of control and could threaten the entire southeastern region of Chad."

It said that since November 4, at least 20 villages south of the eastern town of Goz Beida had been attacked by raiders, who were identified by their victims as Arabs and were often long-standing neighbours.

"They are often well-armed, particularly with Kalashnikovs; on horseback, camelback or in trucks; sometimes in military attire, sometimes in civilian attire," UNHCR said.

Since November 7, about 5,000 newly displaced Chadians had converged on a site for internally displaced people in Habile, 45km southeast of Goz Beida.

Darfur connection

This brought to about 68,000 the number of Chadians displaced by violence in the east over the year.

More than 200,000 Sudanese refugees from Darfur also shelter in Chad.

Chad and its southern neighbour Central African Republic, which is also affected by the violence from Darfur, have called for the deployment of international peacekeepers.

But Sudan has resisted international pressure to allow a stretched African peacekeeping force in Darfur to be put under a UN mandate.