The crew of a US-flagged container ship has retaken control of the ship from Somali pirates, but its captain is being held hostage, the freighter's second officer said Wednesday.

Meanwhile, Pentagon officials said the US Navy destroyer Bainbridge and other ships are on the way to the scene, though they are hundreds of kilometers away.

US presidential foreign policy adviser Denis McDonough said President Barack Obama is following the situation closely.

Richard Phillips, the captain, is being held captive by pirates, Ken Quinn, one of the some 20 crew members onboard, told CNN in a ship-to-shore phone interview.

This undated image shows the 17,000-ton container ship Maersk Alabama, when it was operating under the name Maersk Alva, which has been hijacked by Somalia pirates with 20 crew members aboard, Wednesday April 8, 2009, while sailing from Salalah in Oman to the Kenyan port of Mombassa via Djibouti.[Xinhua]

"There are four Somali pirates, and they've got our captain," he said.

Phillips is being held in the US-flagged ship Maersk Alabama's 8.4-meter lifeboat, Quinn said.

The crew had a plan to make an exchange for their captain.

"We had a pirate we took and kept him for 12 hours," Quinn told CNN.

"We tied him up and he was our prisoner," he said.

The crew gave back their prisoner but the pirates reneged on the plan and are continuing to hold Phillips captive.

"So now we're just trying to offer them whatever we can, food, but it's not working too good," he said.

Quinn said the crew is trying to hold off the pirates for three more hours until a coalition warship is expected to arrive.

The Maersk Alabama was carrying food aid bound for the Kenyan port of Mombasa when it was seized. Twenty American crew members were on board.