A Somali hardline Islamist cleric allegedly linked to al-Qaida says he has assumed leadership of Somalia's main opposition group.

The cleric, Sheik Hassan Dahir Aweys, takes over as head of the Alliance for the Re-Liberation of Somalia (ARS).  The Alliance earlier said it had elected him.

Aweys replaces Sheik Sharif Sheik Ahmed, who denounced the move.

Ahmed's ouster came after he attended U.N.-sponsored peace talks with the government held in Djibouti last month.  During the talks, Ahmed signed a peace agreement with Somalia's Ethiopian-backed transitional government.

Aweys and other hardline members of the opposition boycotted the talks and rejected the agreement, saying it should have included an immediate withdrawal of Ethiopian forces from Somalia.

Separately, Somalia's foreign minister, Ali Ahmed Jama, Wednesday urged the U.N. Security Council to deploy an international peacekeeping force to his country.

Islamist fighters have been waging an insurgency against Somalia's Ethiopian-backed interim government for 18 months.

Sheik Hassan Dahir Aweys (File)

The agreement between Somalia's government and former ARS leader Sheik Sharif Sheik Ahmed calls for Ethiopian troops to withdraw within 120 days if a U.N. stabilization force of sufficient strength is in place to replace them.  

Jama says his government is fully committed to implementing its obligations under the Djibouti agreement, and it expects the ARS to meet its commitments as well.

Somalia has not had a stable central government in 17 years.  

More than 8,500 people have been killed in the violence, while more than a million others have been displaced.