Washington - A US-flagged cargo ship, The Liberty Sun, was attacked by Somali pirates Tuesday while bound for the Kenyan port of Mombasa, but managed to escape capture, CNN reported.

   Quoting a NATO source with direct knowledge of the incident, the US news network said the pirates fired on the cargo ship, which was carrying US food aid for Africa, but were unable to board.

   "The pirates fired rocket-propelled grenades and automatic weapons at the vessel, which sustained damage," said a statement from New York-based Liberty Maritime Corporation, the owners of the ship.

   An email message from a crewman to his mother after the incident said the crew of the vessel were safe and under escort from coalition ships.

   Senior defence officials were quoted as saying the Liberty Sun was being escorted to its destination by the guided missile destroyer USS Bainbridge.

   The Bainbridge was also carrying Richard Phillips, the captain of the container ship Maersk Alabama, which was hijacked last week.

   Phillips spent several days as a hostage of Somali pirates before his rescue by the US Navy on Sunday.