MONROVIA, Liberia ? Liberia’s combatants on Thursday chose a longtime campaigner against rule by warlords to lead the country’s postwar interim government.

The announcement of the selection of Gyude Bryant, a businessman seen as a consensus builder, came at the close of 78 days of tumultuous peace talks in Accra, Ghana.

The top U.N. envoy for Liberia, meanwhile, said he would ask the Security Council for 15,000 troops to secure the peace, which would make it the largest anywhere in the world. The world body has already approved a force, but not its final size.

Speaking in Monrovia, U.N. envoy Jacques Klein, an American, also said he had asked the United States to keep some of its troops here to help train a new army for Liberia — despite President Bush’s commitment to pulling out a roughly 200-strong U.S. deployment by Oct. 1.

“We are hoping the U.S. will take it on,” Klein told The Associated Press.

An 11-member U.N. assessment team arrived in Monrovia, charged with briefing the Security Council before it determines the scope and mission of the already-approved U.N. peace force.

Two rebel movements and the government signed a peace accord Monday, ending the latest in 14 years of militia rivalries that bloodied and ruined Liberia, once sub-Saharan Africa’s richest nation.

The accord followed Charles Taylor’s Aug. 11 resignation and flight into exile under pressure from fellow West African leaders, the United States and rebels laying siege to his capital.

In Accra, the West African mediator for 2 1/2 months of talks sent the combatants home Thursday with an admonishment to keep the peace.

“You have to play your part,” mediator Abdulsalami Abubakar, a retired Nigerian general, said after delegates finished their deliberations before dawn. “Your country has bled for quite some time now.”