The UN secretary-general, Ban Ki-moon, was said to be "concerned" about the US attacks in southern Somalia and fears they may lead to an escalation of hostilities.
 
The UN's chief spokeswoman, Michele Montas, said Ban was also "concerned the impact this could have on the civilian population in southern Somalia and regrets the reported loss of civilian life."
 
Amadeu Altafaj Tardio, a spokesman for the European Commission - the EU's executive office - said: "Any incident of this kind is not helpful in the long term."
 
US confirms air attacks
 
The fugitive leaders of the Islamic courts have repeatedly said that they will launch a guerrilla war against the troops of Ethiopia.
 
The Somali government has previously said that more than 1,000 Islamic courts fighters may still be in the capital.
 
The Somali government and its Ethiopian allies are supported by the US, which has deployed naval ships just off the Somali coast.
 
The US government, meanwhile, confirmed on Tuesday that it had carried out a series of air raids in southern Somalia aimed at killing what it said were members of al-Qaeda in East Africa.
 
The Pentagon did not say whether the attacks on the villages of Hayo and Bankajirow had been a success.
 
The US said its airstrikes were carried out by an AC-130 gunship [EPA] 
"We acknowledge the fact that the United States military did conduct a strike in Somalia," a Pentagon spokesman said.
 
"The target of the strike we believe was the principal al-Qaeda leadership in the region."
 
Local village elders said the raids - carried out with AC-130 "Spectre" gunships - killed at least 20 people, but said they were unable to confirm the identities of the dead.
 
The strike was Washington's first overt military intervention in Somalia since a disastrous peacekeeping mission that ended in 1994.
 
The US Central Command has  dispatched the aircraft carrier USS Dwight D Eisenhower to operate off the coast of Somalia.
 
Continued air strikes
 
Reporting from Mogadishu on Tuesday, Mohammed Adow, Al Jazeera's correspondent, said US forces continued air strikes on southern Somalia, especially on bases that they say are being used by al-Qaeda suspects and Islamic courts fighters.
 
"They continued pounding areas in southern Somalia, especially the southern tip around the border. They attacked areas around towns such as Ras Kamboni where al-Qaeda fighters are alleged to be hiding," Adow said, referring to US forces.
 
"Some of these people are accused of masterminding the 1998 East Africa bombings [that killed 225 people], and include Fazul Abdullah Mohammed, a known explosives expert said to be hiding in Somalia ever since.
 
"Reports from the ground say there have been civilian casualties, with some saying 31 people have been killed, including a newly wed couple."
 
Adow said Abdullahi Yusuf, the Somali president, had approved the US air strikes on Somali soil, arguing that the Americans were justified in tracking down people they considered terrorists.
 
He quoted Yusuf as saying that those targeted were suspects in the East Africa bombings of 1998 and also the 2002 attack on a hotel in Mombasa who were hiding in that part of the country.