Washington: The Justice Department was considering whether to prosecute a Somali pirate in Washington or New York, US officials said following the rescue of a US hostage and the apprehension of his only surviving captor.

The decision will determine where the pirate will be flown in what is shaping up as the first US piracy case in recent memory.

Three pirates were killed on Sunday in a military operation that rescued Captain Richard Phillips, who had been held hostage aboard a lifeboat for days.

A fourth pirate was in discussions with naval authorities about Phillips' fate when the rescue took place.

Both piracy and hostage-taking carry life sentences under US law.

Two US officials, speaking on condition of anonymity because they were not authorized to discuss the case, said the Justice Department is considering whether to leave the case in the hands of federal prosecutors in Washington or New York.

"He's in military custody right now," FBI spokesman John Miller said. "That will change as this becomes more of a criminal issue than a military issue."

Navy Vice Admiral Bill Gortney, commander of US Naval Forces Central Command, said the disposition of the captured pirate had yet to be determined.

"We have multiple avenues," Gortney said at a Pentagon news conference conducted by telephone. "We could possibly bring him back here to the United States and try him since this was an American flag vessel."

He said prosecutors were also considering taking the pirate to Kenya, where the military has an agreement under which captured pirates will be tried. But that agreement has never been used following an attack on a US ship.

Phillips was taken hostage after his cargo ship was attacked by pirates. The crew thwarted the hijacking but the pirates fled with Phillips into a lifeboat.

Officials said the pirate surrendered to US forces. Details of the surrender were not immediately clear but, under international law, the navy has the right to hold pirates captured at sea and does not need to negotiate extradition with another country.