The 306,500-dwt Artemis Glory(built 2006) came under attacked at about 06:35 GMT on Monday whilst sailing south east through the Gulf of Oman.
A UK Royal Fleet Auxiliary ship is said to received a mayday call from the VLCC, which was relayed to the UK Maritime Trade Operations (UKMTO) in Dubai.
UKMTO confirmed with the master of the Artemis Glory that she was being pursued by a skiff with four men on board who were firing upon the vessel.
The US Navy destroyer USS Bulkeley then responded to the mayday and launched her helicopter to investigate the incident.
“The helicopter observed the Artemis Glory under attack by four individuals in a skiff, who were firing upon the ship with small arms,” the US Navy confirmed.
“Under the principle of ‘extended unit self defence’ and in order to provide protection to the crew of the Artemis Glory, Bulkeley’s helicopter engaged the pirates. All of the pirates are believed to have been killed.”
The Panama-flagged VLCC was on route from Saudi Arabia to China with a cargo of crude. None of its 23 crew were injured in the attack.
In March the USS Bulkeley was involved in the arrest of four pirates during an attack on the Mitsui OSK Lines aframax tanker Guanabara (built 2007).
TradeWinds first reported the Artemis Glory’s brush with pirates on Tuesday, when sources had suggested that they had got close enough to unfurl grappling hooks.
It is not clear if they managed to get their hooks over the side of the VLCC, but it is thought the six-metre freeboard helped prevent them getting on board.
Only four VLCCs have ever been hijacked and the largest freeboard of a seized ship is thought to have been seven metres.
It was the fourth merchant ship to run into difficulties with pirates off the coast of Oman in the past few days.
As TradeWinds reported on Monday an RPG was fired at a Maersk LPG carrier over the weekend during one unsuccessful attack.
An MSC boxship and a Gulf Energy Maritime tanker also survived weekend attacks in the region.
Sources say the spate of pirate activity off Oman comes with the monsoon season starting to kick in.
They have moved their activity further north to escape the increasingly choppy waters in the hope of capturing one last prize before conditions make it more difficult to operate skiffs.