MANAMA, BAHRAIN - Security guards onboard the Maersk-Alabama container ship fended off Somali pirates in a shoot-out Wednesday, months after a previous raid ended with the dramatic rescue of the vessel's skipper.

The US ship was attacked 560 nautical miles off the northeast coast of Somalia, the Bahrain-based US Navy's Fifth Fleet said.

Pirates came within 300 yards (275 metres) of the Maersk before being beaten back by a security team using small arms and a pain-inducing acoustic weapon, the navy said in a statement.

In April the ship was briefly seized by pirates, and captain Richard Phillips was held on a pirate skiff for five days.

The standoff was only ended when US navy sharp shooters attacked the vessel, killing three suspected pirates and capturing one.

'The security team embarked aboard Maersk-Alabama responded to the attack by using evasive manoeuvres, long-range acoustic devices and small arms fire,' the Navy said.

'Due to Maersk-Alabama following maritime industry's best practices, such as embarking security teams, the ship was able to prevent being successfully attacked by pirates,' Vice Admiral Bill Gortney, commander of US Naval Forces Central Command, said.

No injuries or damage were reported on board.

The Pentagon later praised the defenses employed by the ship, part of measures recommend to companies plying Somalia's pirate infested waters.

'There is a debate within the shipping industry on whether or not to embark security teams. That's an individual decision,' said Gortney. 'We clearly think that if you value your cargo, you need that last line of defense.'

The world's naval powers last year deployed warships in the Gulf of Aden in an attempt to curb attacks by ransom-hunting pirates seen as a threat to one of the globe's most crucial maritime trade routes.

Pirates have since shifted their focus to the wider Indian Ocean, a huge area much more difficult to patrol, and have ventured as far out as the Seychelles and beyond.