The New Diamond, with a cargo of 270,000 tonnes of crude and 1,700 tonnes of diesel, issued a distress call earlier Thursday, navy spokesman Captain Indika de Silva said.

The vessel had a crew of 23 -- 18 Filipinos and five Greeks. One was missing, another was injured, and the rest were rescued from the Panama-flagged vessel, according to the navy.

"An Indian coast guard vessel and one of our ships are now in the process of dousing the flames that have spread to the deck of the tanker's service area," de Silva told AFP.

There was no immediate danger of a leak from the stricken vessel, he added, which was 60 kilometres (38 miles) from the coastal town of Sangamankandi Point.

The navy spokesman said the missing crew member was a Filipino who could not be accounted for after an explosion in the engine room of the New Diamond, a 330 metres (around 1,080 feet) long very large crude carrier (VLCC).

The ship's third officer, also a Filipino, had suffered serious burn injuries and was taken to a local hospital.

Two Russian warships which were at Sri Lanka's southern port of Hambantota to take on food and water were now headed to the New Diamond's location to help with the rescue.

Neighbouring India was sending three navy vessels and two more coast guard vessels in addition to providing aerial reconnaissance.

One Indian coast guard ship was already trying to put out the flames.

De Silva said rescuers were trying to prevent the fire from spreading to the cargo area and ensuring that there was no leak.

The New Diamond was travelling from Kuwait to the Indian port of Paradip.