Maersk Alabama Captain Richard Phillips is seen at his home in Underhill, Vermont in this undated photo provided by his family April 8, 2009.[Xinhua/Reuters Photo]

Somali pirates are demanding a ransom on Friday after captured U.S. captain failed to make a escape, according to agencies' reports.

Pirates hijacked U.S. cargo ship Maersk Alabama on early Wednesday about 560 kilometers off the coast of Somalia -- the first of its kind to involve an American crew.

The ship freed by its crew was sailing towards the Kenyan port city of Mombasa where it is due on Sunday, a regional maritime official said on Friday, but Captain of the ship, Richard Phillips,is still held by the pirates on a lifeboat the attackers took from Maersk Alabama.

Phillipe jumped into the sea and tried to swim away during the night, but pirates found his attempt and hauled him back quickly, the reports said.

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/AFP Photo]

The escape attempt came as pirates said they were demanding a ransom, but the exact amount they were asking for is unclear so far.

The U.S. freight ship is carrying 232 containers of food distributed by The United Nations' World Food Program (WFP) -- more than 4,000 tons of corn-soya blend for malnourished children and mothers in Somalia and Uganda and nearly 1,000 tons of vegetable oil for refugees in Kenya, according to Peter Smerdon, a WFP spokesperson.

The crew of 20 Americans managed to retake control of the Danish-operated vessel and have been trying to negotiate their captain's release. "We are not afraid of the Americans," one of the pirates reportedly told reporters by satellite phone.

Maritime officials have said negotiations could be lengthy, with the pirates likely to want a hefty ransom for the captain as well as compensation for a boat that was wrecked in the attack.

Somali pirates have stepped up their attacks in recent weeks after a brief lull. The Maersk Alabama was the sixth ship to have been seized since Saturday.

(Xinhua News Agency April 11, 2009)