Somali pirates attacked an American freighter with rockets to "destroy" the ship in revenge for an operation that freed a US captain last weekend, one of their commanders said yesterday.

The freighter escaped the attack late Tuesday, but more vessels have fallen into the hands of marauding Somali bandits. A French warship meanwhile intercepted a pirate "mother ship" and arrested 11 gunmen, the French defence ministry said.

"This attack was the first against our prime target," pirate commander Abdi Garad said of the attack on the Liberty Sun freighter late Tuesday.

"We intended to destroy this American-flagged ship and the crew on board but unfortunately they narrowly escaped us.

"The aim of this attack was totally different. We were not after a ransom. We also assigned a team with special equipment to chase and destroy any ship flying the American flag in retaliation for the brutal killing of our friends."

Pirates have taken four ships since losing two battles with US and French forces at the weekend.

Their latest target was the Liberty Sun which was heading for the Kenyan port of Mombasa with international food aid, the owners said.

The USS Bainbridge, which mounted the operation to rescue the captain of US cargo Maersk Alabama, came to the rescue of the Liberty Sun, officials said.

Crew members gave a dramatic account of the attack.

"We are under attack by pirates, we are being hit by rockets. Also bullets," crewman Thomas Urbik said in email messages, CNN television reported.

"(A) rocket penetrated the bulkhead but the hole is small. Small fire, too, but put out."

Mr Urbik said the US Navy escorted the ship to safety.