Government spokesman Hourmadji Moussa Doumgor said in a statement late Tuesday that the latest fighting broke out Saturday in the eastern region of Sila and left "numerous victims" on both sides.
That followed a report of violence from Chadian government officials who said a small clash between ethnic Arabs and ethnic Africans in another eastern region escalated into a large-scale attack in which Arabs killed 128 Africans on Oct. 31.
The extent of that violence had not been clear until the delegation reached the remote region on Monday.
Arab-African clashes across the border in Sudan's Darfur have undermined stability in a region that includes eastern Chad and the northern Central African Republic. Tensions have been further heightened because Chad accuses Sudan of supporting Chadian rebels and Sudan makes a similar accusation against Chad.
Arabs, among them slave traders, arrived in sub-Saharan Africa generations ago. Intermarriage and the embrace of Islam by many Africans have blurred identities, but an ethnic divide persists. It is exacerbated by a lack of resources in the region, pitting communities against each other in competition for water and land.
Doumgor said heavy weapons were used in the attack in Sila.
"Heavy weapons were, unfortunately, used to spread death and desolation in a region already subjected to attacks from mercenaries coming from Sudan," Doumgor said.
Chad officials routinely use "mercenaries" to refer to Chadian rebels who have bases in Sudan.
"The government has already called the international community's attention to Sudan's exportation of its crisis to Chad," Doumgor said.
The U.N. has authorized 20,000 troops to replace an under-equipped force of 7,000 African Union peacekeepers in Darfur. But Sudan has refused to allow the U.N. peacekeepers in.
"The international community must respond by sending a U.N. peace force before it's too late," Doumgor said.
Sudanese officials were not available for comment.
Chadian state radio reported Wednesday that President Idriss Deby and his foreign, defense and infrastructure ministers went to Libya Tuesday for consultations about regional tensions with Libyan leader Moammar Gadhafi, who has tried to mediate between Chad and Sudan.
The radio quoted Deby as telling Gadhafi that Sudan "continued to arm, train, feed and send mercenaries to destabilize Chad and by extension the entire region."
"Sudan also is stirring up ethnic and tribal hatred in Chad's east," Deby was quoted as saying.
Sudan and Chad severed diplomatic ties in April, but resumed relations in August after a diplomatic initiative led by Senegal's President Abdoulaye Wade and Libya's Gadhafi.
Ethnic African tribes in Darfur who accused their central government of neglect launched a rebellion following years of low-level tribal clashes there. The Sudanese government is accused of responding by unleashing Arab tribal militias who have been linked to atrocities.
More than 200,000 people have died and 2.5 million have been displaced since fighting began in Darfur in early 2003.