Fierce clashes between Somali gunmen killed at least 20 people overnight, including a pregnant woman and her three children, a militia leader said on Thursday, bringing the death toll in five days of fighting to almost 120.

The third round of Mogadishu street battles this year between gunmen allied to Islamic courts and militia from a self-styled anti-terrorist alliance of powerful warlords erupted on Sunday.

Hundreds of people have been wounded in the worst violence in more than a decade, with many more fleeing their homes in the capital of the failed Horn of Africa country.

Militias firing mortars, rocket-propelled grenades and anti- aircraft missiles battled for control of Mogadishu after a brief truce collapsed on Wednesday.

Analysts say Somalia has become a new proxy battleground between Islamic militants and Washington, which is widely believed to be funding the warlords.

Influential Somali Islamist Sheik Dahir Uweys, whose name appears on a U.S. list of most wanted terrorists, has accused Washington of backing the warlords to avenge the killing of American soldiers in Mogadishu in the 1990s during a U.N. peacekeeping mission that ended in humiliation.

U.N. monitors said in a report to the Security Council on Wednesday that they were investigating an unnamed country's violation of an arms embargo through clandestine support for the warlord "Alliance for the Restoration of Peace and Counter-Terrorism."

Although the monitors did not identify the country, Somalia's interim president Abdullahi Yusuf has named the United States as the warlords' backer.

Analysts expect more bloodshed to come.

PHOTO CAPTION

Somali gunmen drive on the runway of the Mogadishu International Airport in a 2003 file photo. (Reuters)