(Adds details, background, edits)

By Omar Hassan

DJIBOUTI, June 9 (Reuters) - Somalia's interim government and some opposition figures signed a peace deal on Monday that called for the rapid deployment of a robust U.N. stabilization force in the Horn of Africa nation.

It was the latest in a string of such agreements. Opposition hardliners in exile and insurgents inside Somalia had dismissed the U.N.-led talks in Djibouti so it was unclear what effect it might have on the ground.

"We have a peace deal," an aide to the U.N. envoy for Somalia, Ahmedou Ould-Abdallah, told Reuters by telephone.

"They agreed on the termination of all acts of armed confrontation -… to come into force 30 days from the signing of the agreement for an initial period of 90 days, renewable."

The main opposition demand has been that Ethiopian soldiers helping the government fight Islamist rebels quit Somali soil.

The aide said Monday's deal planned for Ethiopian forces to leave within 120 days, but that their withdrawal was conditional on "sufficient" U.N. troops being deployed before that.

A six-week peace conference in the capital Mogadishu last year produced various pacts but had no visible impact on an Iraq-style insurgency of roadside bombings, ambushes and assassinations.

Fighting between the guerrillas and allied Somali-Ethiopian troops killed at least 28 people over the weekend in the city.

A contingent of 2,200 African peacekeepers has made little headway stemming the conflict and the United Nations is reluctant to intervene until security improves.

Hopes had dimmed at the Djibouti talks after hardline members of the opposition rubbished other opposition figures who took part.

For days, the delegations also refused to meet face-to-face to discuss ways of ending 18 years of conflict, and only met directly at Monday's signing.

The violence in Somalia has triggered a humanitarian crisis that aid workers say may be the worst in Africa, with at least a million refugees in a nation torn by constant civil conflict since the 1991 toppling of a military dictator by warlords.

Both sides are due to meet again in Mecca, Saudi Arabia, late next month. (Additional reporting and writing by Daniel Wallis in Nairobi; Editing by Janet Lawrence) (For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/)

AlertNet news is provided by