Some analysts fear a power vacuum after the Ethiopians leave
Ethiopia has reaffirmed that it will withdraw its forces from Somalia by the end of the month after confusion over its pullout dates.
Reporters in the Somali capital say residents in Mogadishu expected the troops to have gone by Friday, according to a UN-backed peace deal.
But Ethiopia's ambassador to the UK told the BBC the deadline has always been the end of December.
Ethiopia went into Somalia two years ago to help oust Islamist forces.
But different Islamist insurgent groups have been gaining ground in recent months and now control much of southern Somalia once more.
The Ethiopian and interim Somali government troops are limited to parts of Mogadishu and the central town of Baidoa, where parliament is based.
The BBC's Mohamed Olad Hassan in Mogadishu says people in the capital believe the 120-day deadline for Ethiopia to be out of the country - as stipulated at the signing of the original Djibouti agreement in August - expires on Friday.
However, many issues leading up to the withdrawal have not been completed and have led to confusion over withdrawal dates.
"Our total withdrawal... will be by the end of this month, the prime minister has made it very clear," Berhanu Kebede, the Ethiopian ambassador to the UK, told the BBC Network Africa programme.
Our correspondent says in the past two weeks the Ethiopians have been setting up bases in villages along the tarmac road between the capital and Baidoa - their possible exit road.
A small African Union peacekeeping force has indicated it may leave with the Ethiopians unless it gets reinforcements.
Mr Berhanu said that Ethiopia's presence had given Somalis an opportunity to participate in political dialogue.
"The conducive environment we created has not been properly used both by international community and the Somalis themselves," he said.
About one million people have fled their homes - many after fierce fighting in Mogadishu between Islamists and the Ethiopia-backed government forces.
Some three million people need food aid - about one third of the population.
Somalia has not had a functioning national government since 1991 when warlords overthrew the regime of President Mohamed Siad Barre and then turned on each other.