UNITED NATIONS (Reuters) - The U.N. Security Council agreed on Wednesday to partially lift a decades-old arms embargo on Somalia for one year, allowing the government in Mogadishu to buy light weapons to strengthen its security forces to fight al Qaeda-linked Islamists.

The 15-member council unanimously adopted a British-drafted resolution that also renewed an African Union peacekeeping force for a year and reconfigured the U.N. mission in the Horn of Africa country.

Somalia's government had asked for the arms embargo to be removed entirely and the United States supported that, but other U.N. member states were wary about completely lifting the embargo on a country that is already awash with weapons, diplomats said.

"What we have tried to do is draw a balance between those who wanted an unrestricted lifting of the arms embargo and those who felt it was premature to lift the arms embargo," Britain's U.N. Ambassador Mark Lyall Grant told reporters. "It is a good and strong compromise."

The embargo on Somalia was imposed in 1992 to cut the flow of weapons to warlords, who a year earlier had ousted dictator Mohamed Siad Barre and plunged the country into civil war.

Somalia held its first vote since 1991 last year to elect a president and prime minister.

The Security Council resolution leaves in place a ban on surface-to-air missiles, large-caliber guns, howitzers, cannons and mortars as well as anti-tank guided weapons, mines and night vision weapon sights.

(Reporting by Michelle Nichols; Editing by Doina Chiacu and Christopher Wilson)