Somalia’s Rivals Agree on a Truce : Africa: A cease-fire could be signed in Mogadishu by month’s end. The clan warfare has cost more than 20,000 dead and wounded.

Two Somali groups agreed Friday to halt their bloody clan war, the leader of one delegation announced, and a formal cease-fire is to be signed in Mogadishu, the war-torn Somali capital.

Osman Hasan Ali said the two sides signed the agreement separately with U.N. Undersecretary General James Jonah and representatives of the Arab League, the Organization of African Unity and the Organization of the Islamic Conference.

He said the pact would be effective immediately. “We will communicate to our office of the United Somali Congress only to fire in self-defense,” said Ali.

Ali is a member of the faction of the congress headed by Gen. Mohamed Farrah Aidid. Aidid is battling President Ali Mahdi Mohamed, who heads a rival faction of the party.

More than 20,000 people have been killed or wounded in three months of fighting between the two factions.

“This will be something our people have long awaited,” Ali said. He said he hoped the cease-fire would be signed in Mogadishu by the end of the month, and that a national reconciliation conference would soon follow.

Somali politics are organized on the basis of clans, several of which now claim power in other sections of the Horn of Africa nation.

The United Somali Congress is essentially the political wing of the Habiiye clan.

Central authority dissolved following the armed overthrow in January, 1991, of President Mohamed Siad Barre, who had ruled Somalia for 20 years.

It was not known how the halt and cease-fire would be monitored.