Attackers have fired four mortar bombs at an Ethiopian military camp close to Mogadishu.
The attack, on Friday night in Darmoley, 10km north of Mogadishu, comes as Michael Ranneberger, the US ambassador to Kenya, told Al Jazeera he believes that some members of the Islamic Courts Union may still have a role to play in Somalia's future.
Speaking to Al Jazeera, Ranneberger said he met Sheikh Sharif Sheikh Ahmed, an Islamic courts leader, and could see him making a contribution to Somalia's future.
But he said the government was waiting for "an indication from the Islamic courts that they do actually want to play a role".
He said: "I don't see the Islamic courts being involved in a future government, but I do see the possibility that individuals within the Islamic courts, such as Sheikh Sharif, could play a role."
The mortar strike on Friday was the latest assault on government and Ethiopian troops since they routed Islamic courts fighters and seized Mogadishu last month.
"I believe peace is possible only if foreign intervension stops"
Warsameh, Mogadishu, Somalia
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A government source was reported as saying: "An unknown gunman carried out four mortar attacks aimed at an Ethiopian base in Darmoley. I have no information of any wounded or dead."
Meanwhile, according to Abdirahman Dinari, a government spokesman, police were interrogating a man over a mortar attack on Mogadishu international airport on Wednesday that injured five people.
Dinari said: "The police have arrested a man suspected to have been behind the attack on the airport. They are questioning him."
Dinari also said 23 people, including senior Islamic courts officials, have been handed over to the government by the Kenyan authorities who arrested them attempting to cross the border.
Many suspect the attacks are carried out by remaining members of the Islamic courts, although some have suggested the attackers may be criminals or rival tribal leaders.
|Sheikh Sharif is considered a moderate in the|
Islamic courts movement [AFP]
Ethiopian troops began to withdraw from Mogadishu on January 23, but there are concerns that without Ethiopian military backing the government will not be strong enough to prevent Somalia sliding back into the sectional conflicts the country experienced since 1991, when Mohamed Siad Barre, Somalia's former leader, was ousted.
The government has asked for international peacekeeping troops to be sent to the country.
The African Union has backed a force of almost 8,000 to replace the withdrawing Ethiopian soldiers.
Uganda, Malawi and Nigeria have pledged troops, but South Africa and Rwanda have ruled out deploying their forces.
Mozambique and others are considering contributing.