Islamists once more control much of Mogadishu
The last Ethiopian troops in Somalia's capital have left Mogadishu and Islamist forces have taken over most of the bases they have left behind.
A BBC reporter says four of the six vacated bases have been taken over by insurgents from different factions, seemingly working together.
Troops loyal to the interim government, which Ethiopia was supporting, have control of only two of the bases.
Meanwhile, Prime Minister Nur Hassan Hussein says he wants to be president.
Abdullahi Yusuf resigned as president last month after falling out with Mr Hussein over attempts to negotiate a peace deal with the Islamist-led armed opposition.
But the opposition is split into various factions, and the more hardline groups do not support the peace process.
Ethiopia intervened in Somalia two years to help oust Islamists, who had taken control of much of the south of the country.
The BBC's Mohamed Dhore in Mogadishu says African Union peacekeepers are guarding Mogadishu's presidential palace, but most positions in the capital have been filled by Islamist insurgents.
He says government troops are in the former Ethiopian base at the southern entrance to the city and at the empty central hospital, Digfer.
Analysts had feared the withdrawal of the Ethiopians would lead to a power vacuum and fighting between rival Islamist factions.
But at the moment all factions - whether they back the peace process with the government or not - seem to be working together.
Some 16,000 civilians have been killed in the conflict between Somalia's transitional government and the Islamists, and a million more have been forced from their homes.
Correspondents say that Mr Hussein - one of the architects of the peace deal - is hoping to capitalise on the Ethiopian withdrawal to win support for his presidential candidacy.
Mr Hussein, a former humanitarian worker from Mogadishu and a member of the area's dominant Hawiye clan, has the backing of Igad, the East African regional grouping which brokered the agreement that led to the formation of the interim government in 2004.
"Today I want to announce that I am a candidate for the post of president which is expected to be contested soon and whoever wins it should peacefully and democratically run the country," Mr Hussein said.
Meanwhile, Ethiopian Prime Minister Meles Zenawi has been defending his decision to oust Islamists two years ago.
Thousands of Mogadishu's residents have fled over the last two years
He said the reason Ethiopia had intervened was to avert a clear and present danger to its own security and because it was asked to by the Somali transitional government.
Bringing peace and stability was something Somalis could only do themselves, he said.
Speaking at a news conference in the Ethiopia capital, Addis Ababa, he said that with hindsight, he would do the same again.
"I would without hesitation, have intervened again if I had to do it all over again," he said.
"Now that does not mean I would repeat all the specifics of that intervention.
"Only stupid people would repeat everything they did in the past. So obviously if we were to do it again we would do it better. But we would do it nonetheless."
He however said Ethiopian troops would not be rushed into leaving the rest of the country - and that they would remain in force along the border.
The US wants the United Nations to take over peacekeeping duties from the African Union.
But last month UN Secretary General Ban Ki-moon said few countries were willing to send troops to Somalia, as there was no peace to keep.
Somalia has not had an effective national government since 1991, since when various militias have been battling for control.