Khartoum, Sudan ? A top Sudanese official on Tuesday defended an accused ringleader of Arab militia attacks on African villagers as a legitimate tribal leader and warned any attempt to go after such men could ignite warfare that would tear the country apart.

Separately, the U.N. refugee chief said Khartoum had agreed to a stepped-up U.N. civilian role and possible expansion of an African Union monitoring team in the western Sudanese region of Darfur, where 19 months of conflict have left more than 50,000 dead and uprooted 1.4 million.

The U.S. State Department has named Sheik Musa Hilal and six other Sudanese as suspected coordinators of the government-allied Janjaweed, the Arab militia largely blamed for the violence in Darfur.

But Sudan’s state minister for foreign affairs defended Hilal as a prominent tribal chief.

Hilal “has nothing to do with the Janjaweed. He is a tribal leader, of a very big, very significant tribe,” Minister Najeib el-Kheir Abdelwahab said in an interview.

Sudan welcomed any international attempt to pinpoint Janjaweed leaders, Abdelwahab said. But “by not adequately identifying the leaders of the Janjaweed, by pointing to some tribal leaders … if we are not cautious about that, you will ignite a significant tribal conflagration.”

“And this can lead … to the dismemberment of Sudan,” the Sudanese minister warned.

Darfur’s bloodletting started in February 2003, when two non-Arab African rebel groups launched attacks primarily on government and military targets to press demands for a greater share of power for Darfur.

Hilal has led Darfur’s Arab Um Jalloul tribe for the past two decades. According to some international officials, Hilal used government funds to rally Arabs and set up militia training camps to quash the rebellions.

The Sudanese military and Janjaweed militia are accused of bombing runs and horseback raids that destroyed non-Arab villages. Residents have been killed, raped and driven from their homes. The United States, European Parliament and others say the campaign amounted to genocide.

Meanwhile, the U.N. refugee chief ended a five-day mission to Sudan and said the Arab-dominated government had taken steps to lessen the violence.

But attacks persist, and Darfur’s people now have “zero trust” in their government to protect them, said Ruud Lubbers, the U.N. High Commissioner for Refugees.

As a result, Sudanese leaders agreed to a stepped-up civilian U.N. role to monitor rights violations, including teams of women to investigate complaints of Darfur’s women and children.