Chad has declared a state of emergency in three eastern regions where ethnic clashes have left as many as 200 people dead and raised fears that Sudan's Darfur conflict is spilling across the border.

The government said the violence appears to be between Chadians but accused Sudan of instigating the clashes in the Ouaddai, Wadi Fira and Salamat regions, which border the Darfur region.

"By exporting its Darfur conflict to Chad, Sudan wants to weaken Chad by making different Chadian communities fight each other. All this is to prepare the ground for a large-scale war," government spokesman Hourmadji Moussa Doumgor said Monday.

Chad says the fighting began Oct. 31, when a small clash between ethnic Arabs and ethnic Africans escalated into a large-scale attack in which Arabs killed 128 Africans.

As many as 200 people have been died and nine villages looted, the U.N. refugee agency said last week after it sent a team to the region to investigate reports of armed men on horseback attacking and burning the villages.

The UNHCR said the violence resembles that in Darfur and called for urgent action.

In Darfur, ethnic African tribes accusing the central government of neglect launched a rebellion three years ago, following years of low-level tribal clashes. The government is accused of responding by unleashing ethnic Arab tribal militias who have been linked to atrocities.

More than 200,000 people have died and 2.5 million have been displaced. Eastern Chad is home to more than 200,000 Sudanese refugees.

Arabs, among them slave traders, first reached sub-Saharan Africa more than a century ago. Intermarriage and the embrace of Islam by many Africans have blurred identities, but an Arab-African divide persists. It is exacerbated by a lack of resources in the region, pitting communities against each other in a competition for water and land.