Somali pirates said today that they had released the Sirius Star, the oil-laden supertanker seized in the Indian Ocean in November, in return for a $3 million ransom.

Photos taken by the US Navy appeared to show to the ransom payment being parachuted on to the deck of the Sirius Star from a light aircraft.

The 25 crew, including two Britons, have been help captive on the ship for almost two months. The pirates said that they were all unharmed.

“All our people have now left the Sirius Star. The ship is free, the crew is free,” said Mohamed Said by telephone from the pirate base of Harardhere, on the central Somalia coat.

The ship's owner, a Dubai-based subsidiary of the Saudi oil company Aramco, would not immediately confirm the claim. But a regional maritime organisaition said the ship was free. "The last batch of gunmen have disembarked from the Sirius Star. She is now steaming out to safe waters," said Andrew Mwangura of the East African Seafarers Assistance Programme, which is based in Mombasa, Kenya.

A ransom of $3 million has been paid, said an associate of the pirates in Haradhere. A demand of $25 million (£17 million) was made after the ship's capture, but recent reports have suggested the pirates had reduced this significantly. The Saudi Foreign ministry has been negotiating with the ship's captors since it was seized on November 16.

The two Britons on board are Chief Engineer Peter French and second officer James Grady. The Foreign Office said it was "urgently looking into" reports of their release. There are 19 Filipinos, two Poles, a Croat and a Saudi in the rest of the crew.

The Sirius Star, fully laden with two million barrels of oil worth about $100 million, was hijacked 420 miles off the the African coast in the most dramatic example yet of the growing reach and sophistication of Somali pirate activities.

The spectacular capture of a ship the size of an aircraft carrier, 330 metres long and weighing 318,000 tonnes, has prompted intensive diplomatic and military activity against the Somali pirates. EU, American and Chinese warships now patrol the Gulf of Aden and last month the UN Security Council passed a resolution allowing international forces to fight the pirates on Somali land.

“While the potential release of the Sirius Star is undoubtedly excellent news, we must not forget that nearly three hundred other merchant mariners are still being held captive. The men who attacked the ship and held the crew hostage are armed criminals, and consequently we must remain steadfast in our efforts to address the international problem of piracy,” said Commodore Tim Lowe, deputy commander of the US-led Combined Maritime Forces.

Pirates operating out of Somalia were responsible for more than 100 attacks last year in the Gulf and Aden and the Indian Ocean. There are thought to be 15 vessels still held by pirates in Somalia. Among those is the MV Faina, a Ukrainian cargo ship seized in September which is carring 33 battle tanks.

A report by Chatham House, a think tank, estimated that more than $30 million in ransoms were paid last year to pirates. With such a huge revenue stream, they are able to equip themselves with the latest weaponry. Their simple boats contain rocket-propelled grenade launchers that could stop a tank. Unarmed cargo ships have little option but to submit.

While international forces - including the Royal Navy frigate Cumberland - have succesfully helped fight off pirate attack, they have held back from attacking hijacked ships for fear they could endanger the crew. Most hijackings are thought to end with a ransom payment.

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