Somali pirates have hijacked a United States-owned tugboat in the Gulf of Aden with 16 crew on board.
Maritime industry sources say the tug, which sails under an Italian flag, was towing two barges at the time of the attack. The crew are reported to be unharmed.
Meanwhile pirates holding an American captain hostage have warned that using force to rescue him could result in disaster.
Captain Richard Phillips' ship, the Maersk Alabama, has now arrived in the Kenyan port of Mombasa.
But the head of Maersk Line Shipping John Reinhart says the crew will have to remain onboard while the attack is investigated.
Captain Phillips was taken prisoner on Wednesday. The pirates say they hope to transfer him from a lifeboat to a bigger vessel.
He tried to escape on Friday by jumping overboard and swimming to a nearby US ship, but was recaptured.
