US Secretary of State Hillary Clinton says the United States will seek a broader international effort to fight piracy, and will send an envoy to a Somali donors conference this week.
Heavily armed pirates from Somalia have been increasingly striking the busy Indian Ocean shipping lanes and strategic Gulf of Aden, capturing dozens of vessels, hundreds of hostages and making off with millions of dollars in ransoms.
On Sunday, US Navy snipers killed three Somali pirates and freed an American ship captain who had been held hostage for five days.
Mrs Clinton said the United States will explore efforts to track and freeze pirate assets. Its envoy will help Somalia to crack down on pirate bases and to find ways of decreasing incentives for young Somali men to engage in piracy.
"We may be dealing with a 17th-century crime, but we need to bring 21st century assets to bear," Mrs Clinton said.
French detain 11 Somali pirates, ship freed
The French navy has detained 11 Somali pirates who tried to seize a Liberian-flagged merchant ship.
The French Defence Ministry says its frigate Nivose captured the pirates' mothership, which was carrying two small assault boats, some 900km east of the Kenyan port of Mombasa.
The frigate tracked the pirates after its helicopter thwarted an attack on the Liberian-flagged Safmarine Asia.
Supported by a surveillance plane, France's frigate is in the region as part of the European Union's anti-piracy mission that also involves German, Spanish, French and Italian forces.
In Athens, the Greek Merchant Marine Ministry said the Saint-Vincent-flagged cargo ship Titan and its 24 crew were freed by their Somali captors on Wednesday.
The vessel was seized in March on its way from the Black Sea to Korea.