On Saturday, two U.S. Navy ships, killing one suspect and wounding five others.
It said that the incident took place on international waters and the Navy had taken 12 suspects, including the wounded, into custody after the gunbattle.
Saleban Aadan Barqad, a spokesman for the militias, confirmed the casualties Sunday to The Associated Press.
He said that in total 27 Somali militiamen had been patrolling off the Somali coast before the gunbattle. Fourteen returned to shore safely, Barqad said on two-way radio from the central Somali town of Harardhere.
The U.S. Navy opened fire first on the Somali militiamen's small utility boat, which was towing a pair of skiffs, said Barqad. His statement contradicted U.S. claims that the navy vessels were fired upon.
Barqad said that the boat caught fire, but did not explain how.
The militiamen, "were in an operation to protect the country's sea resources from illicit exploitation by foreign vessels," Barqad said.
Geraad Mohamud, also from the same militia group, threatened that they would kill any hostage they capture and that they would attack any ship unlawfully plying Somali waters unless their men were released.
Lt. Cmdr. Charlie Brown, spokesman for the U.S. Navy's 5th Fleet, said on Saturday that the shootout ensued after the Navy ships, patrolling the area as part of a Dutch-led coalition task force, spotted the suspect 30-foot-long fishing boat towing smaller skiffs and prepared to board and inspect the vessels.
No sailors were wounded in the battle, which occurred at about 5:40 a.m. local time Saturday, approximately 25 nautical miles off the Somali coast in international waters.
A statement from the Bahrain-based 5th Fleet said the suspected pirates were holding what appeared to be rocket-propelled grenade launchers.
When the suspects began shooting, naval gunners on the American ships returned fire with mounted machine guns, killing one man and igniting a fire on the vessel.
Three suspects were seriously wounded and being treated on one of the Navy ships, Brown told The Associated Press. A Dutch Navy medical team was en route aboard the HNLMS Amsterdam.
The Navy boarding teams confiscated an RPG launcher and automatic weapons, the statement said.
The Navy said the incident involving the Norfolk, Virginia-based USS Cape St. George and USS Gonzalez occurred approximately 25 nautical miles off the Somali coast in international waters.
Piracy on Somali waters steeply increased last year, with the number of incidents rising to 35, compared with only two in 2004, according to the International Maritime Bureau. The increase in piracy included first-time attacks on vessels carrying food aid for Somalis and a cruise ship.
Somalia has not had a coast guard or navy since 1991 when warlords ousted a dictatorship and then turned on each other.
The troubles facing Somalia's fledging 17-month old transitional government, including piracy, will be discussed at regional leaders' meeting Monday.
The International Maritime Organization has warned ships to stay away from the Somali coast because of pirate attacks, which surged to 35 last year from two in 2004.
On Friday, Kenyan Foreign Affairs Minister Raphael Tuju renewed a call for a peacekeeping mission to Somalia to help disarm the country's various militias.
Failure to do that will "lead to an increase in piracy, proliferation of illicit small arms and light weapons will continue unabated, and organized criminal activities will escalate," Tuju told his counterparts from the eastern Africa region.
On March 15, the U.N. Security Council encouraged naval forces operating off Somalia to take action against suspected piracy. Pirate attacks against aid ships have hindered U.N. efforts to provide relief to the victims of a severe drought in the area.