A US warship and negotiators from the Federal Bureau of Investigation were called in to help on Thursday, one day after a US-flagged cargo ship was attacked by pirates off the coast of Somalia.

US Secretary of State Hillary Clinton (2nd R), US Defense Secretary Robert M. Gates (1st R), visiting Australian Defense Minister Joel Fitzgibbon (1st L) and Australian Minister for Foreign Affairs Stephen Smith (2nd L) hold a joint news conference at the US State Department in Washington DC, capital of the United States, April 9, 2009. Hillary commented on the crisis with Somali pirates off the African coast during the news conference. [Zhang Yan/Xinhua]

The Pentagon said the USS Bainbridge, a guided-missile destroyer, has arrived on the scene and was closely watching the situation.

FBI negotiators also were called in to help facilitate the release of the cargo ship captain still held by pirates, said FBI spokesman Bill Carter.

Captain Richard Phillips was being held on a lifeboat that was believed to be near the cargo ship Maersk Alabama.

Kevin Speers, a spokesman for the ship's owner, the Norfolk, Virginia-based Maersk Line Ltd, a subsidiary of Denmark's A.P. Moller-Maersk, told reporters Phillips has not been harmed.

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]