Somali pirates released an Italian-owned oil tanker and its 22 crew on Wednesday after receiving a multi-million dollar ransom, one of the pirates told Reuters.

Italian Prime Minister Mario Monti expressed great satisfaction at the release of the Savina Caylyn tanker and its crew of five Italians and 17 Indians.

The tanker had been seized in early February.

The ransom was dropped from an aircraft in two stages, according to a pirate speaking to Reuters by phone.

We have just received the remaining $3 million (1 million pounds) of the agreed $11.5 million ransom. We have abandoned the ship, a pirate calling himself Abdiwali said from Haradhere, one of the pirates' biggest coastal bases.

The pirates released the tanker's Indian crew members after the first ransom drop was made, Abdiwali said, awaiting the second instalment before releasing the five Italian sailors a few hours later.

There was no comment in Italy over the ransom.

Seaborne gangs are making tens of millions of dollars in ransoms, and despite successful efforts to quell attacks in the Gulf of Aden, international navies have struggled to contain piracy in the Indian Ocean owing to the vast distances involved.

Andrew Mwangura, a former regional maritime official and maritime editor of the online Somalia Report, said it was not yet clear if the tanker had begun sailing away from the Somali coast.

The medium-sized tanker was seized by an armed gang firing guns and rocket propelled grenades some 500 miles off the coast of India and 800 miles off Somalia, as the vessel transited from Sudan to Malaysia. It was loaded at the time.

The Aframax-type tanker can carry a maximum of just over 700,000 barrels of oil. The largest crude tankers carry maximum cargoes of between 2 to 3 million barrels of oil.

(Additional reporting by Catherine Hornby in Rome; Editing by Richard Lough and Alessandra Rizzo)