Washington - Crew members may have retaken control of a US- operated ship that was hijacked off the coast of Somalia, CNN reported citing an unnamed Pentagon official.

The ship with 20 US citizens on board was taken by Somali pirates early Wednesday morning, the first time a US crew has been taken hostage in the volatile waters.

At least one of the pirates had been taken into custody by the crew and another three of the hijackers had attempted to escape, according to CNN.

The US State Department would not confirm that the ship was recaptured. Spokesman Robert Wood said there were still a number of "contradictory reports" coming out of the region.

Owned by Danish firm Maersk and operated by US company Maersk Line Limited, the ship was carrying food supplies and no weapons, and was headed to Mombasa, Kenya, according to John Reinhart, chief executive of Maersk Line.

"This was going to Africa for people who are in need," Reinhart told reporters from the company's headquarters in Norfolk, Virginia.

Reinhart also would not confirm that the ship had been retaken, saying it was a fluid situation. Reinhart said he had earlier been in contact with a crew member by mobile phone and that all 21 on board were apparently safe.

The White House earlier said it was "closely monitoring" the situation. A spokesman for the US Navy's Fifth Fleet stationed in Bahrain said a coalition force off the Somali coast was keeping watch on the vessel.

Somali pirates, who typically seek ransom, have stepped up their attacks on ships operating off the coast in recent months. The Danish-US ship is the sixth to be seized since Saturday.