MOGADISHU - Ethiopian troops whose military strength was crucial to helping Somalia's government drive out a radical Islamic militia began withdrawing Tuesday, raising fears of a power vacuum unless peacekeepers arrive soon in this chaotic nation.

Somali government spokesman Abdirahman Dinari said Ethiopia helped chase out the Council of Islamic Courts militia, which had taken over the capital and much of southern Somalia. But it was time for the neighbouring forces to leave.

"As of today, the Ethiopian troops have started to withdraw from Somalia. We are grateful that they played an important role in the restoration of law and order in the country,'' Dinari said.

Ethiopia's government spokesman, Zemedkun Tekle, confirmed Tuesday's pullout but gave no details.

The intervention of Ethiopia last month enabled a military advance that proved a stunning turnaround for Somalia's two-year-old government. Without Ethiopia's tanks and fighter jets, the administration could barely assert control outside one southern town and could not enter the capital.

But the potential for violence in this Horn of Africa nation remains great because of clan rivalries, resentment of the government's Ethiopian backers and a threat of guerrilla war from remnants of the Islamic movement.

Nearly 200 people gathered at the former National University in Mogadishu, cheering as the Ethiopians moved out on trucks and tanks.

"Leave us alone and let us solve our problems,'' the crowd chanted.

The withdrawal gave a sense of urgency to the arrival of a proposed African peacekeeping force. The African Union has approved a plan to send about 8,000 peacekeepers for a six-month mission that would eventually be taken over by the UN

Many Somalis were angered by the presence of Ethiopian forces. Somalia, a Muslim country, and Ethiopia, which has a large Christian population, fought a brutal war in 1977.

"I am very happy the Ethiopians are leaving because it will end clashes in which civilians are the victims,'' said Ilmi Shardi Mahad, a resident of Mogadishu's Hurwa district, considered a hotbed of support for the Islamists.

The Islamic council has played on the traditional Somali-Ethiopian rivalry, saying the group would launch an Iraq-style guerrilla war on Ethiopian troops here.

"The withdrawal of Ethiopia will be the end of our ongoing insurgency,'' said Sheik Ahmed Muumin, a member of the Islamic council who contacted The Associated Press by telephone on Tuesday.

But it was not clear whether his views represented those of the Islamic leadership, which is largely in hiding.

One top leader of the ousted movement, apparently afraid for his life, turned himself in to authorities in neighbouring Kenya on Sunday and is in custody. Sheik Sharif Sheik Ahmed, considered by American officials a moderate who could contribute to rebuilding Somalia, is not believed to be wanted by the authorities.

U.S. Ambassador to Kenya Michael Ranneberger, who also represents U.S. interests in Somalia, plans to meet with Ahmed this week to "urge Sheik Sharif to counsel his supporters not to carry out violence and to support the development of an inclusive government,'' the U.S. Embassy said.

Ahmed was the chairman of the Executive Council of Islamic Courts and shared the leadership with Sheik Hassan Dahir Aweys, who was chairman of the court's legislative council. Aweys is on a U.S. list of people with suspected ties to al-Qaida, though he has repeatedly denied having ties to international terrorists.

In a newly released videotape, al-Qaida's deputy leader Ayman al-Zawahri vowed that the mujahedeen would "break (the) backs'' of the Ethiopians in Somalia.