Eleven Somalis accused of attacking two US warships off Africa's east coast were brought to the United States and have been charged with piracy, the Department of Justice said Friday.

Five of the men were indicted for attacking the heavily armed USS Nicholas on March 31 in a brazen attempt to rob the ship and piracy, and the other six were also charged with acts of piracy against the USS Ashland on April 10, court documents showed.

In the case of the US Navy frigate Nicholas, two of the defendants, Gabul Abdullah Ali and Abdi Wali Dire, "opened fire with their assault firearms on what they believed to be a merchant ship."

The same error of judgement was not noted for the six who moved on the assault landing craft USS Ashland, but all eleven were indicted for piracy, attacking "to plunder" a maritime vessel, and assault with a dangerous weapon, among other charges.

The five accused of attacking the Nicholas are due in court in Norfolk, Virginia at 1700 GMT, and the other six are to appear at 1730 GMT.

The United States had been considering the legal fate of the five suspected Nicholas attackers since they were picked up near the Seychelles after opening fire from a skiff on the missile-guided frigate, which returned fire and quickly chased down their small boat.

The Ashland had been hit on its port side in Gulf of Aden by light arms fire by the six suspected pirates, also operating from a small skiff, the US Bahrain-based command said at the time.

The end of the winter monsoon in the region has spurred a fresh spate of attacks by pirates able to venture hundreds of miles (kilometers) from their bases and approach their prey on relatively calm seas.

Armed with AK-47s, GPS navigation and satellite phones, pirates raked in an estimated 60 million dollars in ransoms last year.

They are often detained but then let go days later by foreign navies patrolling the region.

Kenya, south of the pirates homeland in Somalia, is no longer willing to take custody pirate suspects detained by international navies off the coast, but Admiral Mark Fitzgerald told reporters at a Pentagon briefing earlier this month that US officials were approaching other countries to take them in.

"We could put fleets of ships out there, we could put a World War II fleet of ships out there and we still wouldn't be able to cover the whole ocean," he said.

Somalis enriched by their banditry off the coast are buying up properties in the Kenyan capital Nairobi and in Mombasa, as well as in Addis Ababa in Ethiopia, said Fitzgerald, commander of US naval forces in Europe and Africa, who urged anti-piracy efforts to "go after the money."

Efforts to track finances need not be US-led, but should be placed under an international "framework," he said in an April 10 briefing, pointing to the United Nations or the European Union.