Somali pirates freed a Saudi supertanker seized in the world's biggest ship hijacking for a $3 million ransom today.

The capture of the Sirius Star and its $100 million cargo of crude in November drew attention to a surge in piracy off Somalia that has brought global navies rushing to protect one of the world's most important shipping lanes.

Farah Osman, an associate of the pirates speaking to Reuters from Haradheere port near where the tanker was held, said the gang had wanted more money but finally agreed $3 million. "The pirates are now arguing about division of the money," he said.

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A regional maritime group confirmed the release.

"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, based in the Kenyan port of Mombasa.

There was no immediate comment from Vela International, the Dubai-based shipping arm of Saudi Aramco, which operates the ship. It was heading south, possibly to anchor off Mombasa for resupplying or to go on to South Africa, Mwangura said.

The Sirius Star was captured in November with 25 crew members, 450 nautical miles southeast of Kenya in the boldest seizure to date by Somali pirates.

The rampant piracy off Somalia worsened dramatically in 2008 as an Islamist insurgency fuelled chaos onshore.

The piracy in the busy Gulf of Aden and Indian Ocean shipping lanes has sent shipping insurance prices soaring, made some owners choose to go round South Africa instead of through the Suez Canal, and brought an unprecedented deployment of international warships to the region.

The crew of the Sirius are from Britain, Poland, Croatia, Saudi Arabia and the Philippines.

The US Navy, which has had a warship close to the Sirius monitoring the saga, could not immediately confirm its release.

The US Navy said yesterday it was planning to launch a force to combat piracy in the Gulf of Aden, an offshoot of an earlier mission. Chinese warships also began anti-piracy patrols off Somalia this week.

Spain will send up to 395 military personnel and a patrol plane to the waters off Somalia to defend merchant ships from pirates, the government said on Friday.

Underlining the danger, Kenya Ports Authority said on Friday that Somali pirates had attacked a Kenyan fishing vessel north of Mombasa, kidnapping three Indian nationals on board.

Neither the ship nor Kenyan crew, however, were taken, officials said, adding full details of the incident yesterday in waters near the Somali border were still not available.