Somali pirates on Monday vowed to retaliate for the deaths of three colleagues who were shot dead by US Navy snipers hours before in a daring nighttime assault that freed a 53-year-old American captain.

The Navy Seals late Sunday rescued freighter Capt Richard Phillips, who had been held by pirates on a lifeboat that drifted in the Indian Ocean for five days.

"Every country will be treated the way it treats us," said Abdullahi Lami, one of the pirates holding a Greek ship anchored in the pirate den of Gaan, a central Somali town.

"In the future, America will be the one mourning and crying," he said. "We will retaliate for the killings of our men."

He gave no details and it was not clear in what way the pirates could retaliate, though some fear they could take their revenge on the hundreds of other foreign nationals they hold on seized ships.

The rescue dealt a blow to pirates who regularly seize passing ships and hold them captive until multimillion dollar ransoms are paid. But it is unlikely to help quell the region's growing pirate threat, which has turned the Gulf of Aden and the waterways along Somalia's coast into some of the most dangerous shipping lanes on the planet.

Pirates currently hold more than a dozen foreign ships, most moored along the Horn of Africa nation's long coast, with about 230 foreign sailors from Russia to the Philippines.