"Foreigners were fighting alongside the local terrorists and were killed," said Hussein Gutale Ragheh, a spokesman for the secular alliance. No one was caught alive, he said, but among the dead were Arabs and others who looked like Pakistanis, Sudanese and Oromo fighters from neighboring Ethiopia.
The report could not be independently verified, but the possible presence of foreign extremists has heightened fears that Al Qaeda is making Somalia a staging ground, a State Department spokesman said Wednesday.
The U.S. is widely believed to be supporting the alliance of secular warlords, but American officials refused Wednesday to confirm or deny that.
"Our concerns with regard to Somalia and terrorism lie primarily in the potential presence of foreign fighters in Somalia," State Department spokesman Sean McCormack said. The U.S. is working with a wide spectrum of leaders, and he said he did not know if that included the warlords currently battling Islamic leaders for control of the capital, Mogadishu.
"In an environment of instability, as we've seen in the past, al-Qaida may take root, and we want to make sure that al-Qaida does not in fact establish a beachhead in Somalia," White House Spokesman Tony Snow said Wednesday.
Somalia, which has had no effective central government in 15 years, has been roiled by a surge in violence that killed more than 140 people in and around Mogadishu.
Somalia's fundamentalists portray themselves as capable of bringing order to the Horn of Africa country. Their growth in popularity and strength, and the possibility that they have outside support, is reminiscent of the rise of the Taliban in Afghanistan in the late 1990s.
Somalia's descent into chaos began with the 1991 overthrow of longtime dictator Mohamed Siad Barre. Since then, warlords who divided the country into clan-based fiefdoms have fought one another, though some recently joined a U.N.-backed interim government trying to assert control.
The recent death toll is among the worst in the decade of near-chaos.
Most victims in more than a week of fighting have been passers-by caught in crossfire or hit by shells gone astray.
On Wednesday, hundreds marched through Mogadishu chanting, "Down with the warmongers and down with their supporters!" and carrying signs saying "War is not a solution." But some civil groups who had helped plan the rally boycotted it after militia members showed up.
A cease-fire was signed over the weekend, but its effect was limited. Two people were killed Wednesday outside the capital.
The mayor of Mogadishu, who has ties to the Islamic militia, denied that foreigners were involved.
"This is really a typical civil war," Mohamud Hassan Ali told The Associated Press. But he added that he was investigating reports that the alliance had turned over suspected al-Qaida militants to the U.S.
"We have heard the reports but we don't have any confirmation yet," Ali said.
The secular alliance, which includes members of the interim government but acts independently of it, accuses the Islamic militiamen of having ties to al-Qaida. The Islamic group accuses the secularists of being puppets of the United States.
Abdullahi Yusuf Ahmed, president of Somalia's near-powerless transitional national government, told The Associated Press earlier this month that he believes Washington is supporting the secular militia as a way of fighting several senior al-Qaida operatives who are protected by radical clerics in Somalia. He called on Washington to instead work only with his government.