India on Tuesday sent fresh supplies of firefighting chemicals to help battle a new blaze on a stricken tanker loaded with a massive cargo of crude oil off Sri Lanka's eastern coast.

The New Diamond has been burning since Thursday, and a huge blaze believed to have been extinguished on Sunday reignited because of strong winds on Monday, raising fears of another environmental disaster in the Indian Ocean.

Rescuers and salvage experts have said there is no sign of a leak in the Panama-flagged supertanker, which was carrying 270,000 tonnes of crude and another 1,700 tonnes of diesel as its fuel.

Ramping up the rescue effort, an Indian Coast Guard aircraft was expected to bring dry chemical powder on Tuesday, which would then be dropped by helicopters on the ship, the Sri Lankan navy said.

The New Diamond, a supertanker carrying 270,000 tonnes of crude oil, has been ablaze for days off the coast of Sri Lanka
The New Diamond, a supertanker carrying 270,000 tonnes of crude oil, has been ablaze for days off the coast of Sri Lanka Sri Lanka's Air Force / -

Six salvage experts and 11 disaster management professionals flown in by the New Diamond's Greek owners were taken Monday to the vessel, some 55 kilometres (34 miles) off the coastal village of Sangamankanda Point, the navy said.

SMIT, a Dutch salvage company, said the stern was still too hot and unsafe for them to board the vessel for an inspection.

"Once the situation is deemed stable and safe, we will be able to inspect the vessel," SMIT told AFP in The Hague.

The company said there was a possibility of towing the tanker to a safer location and removing the cargo.

The fire started after an explosion in the boiler room while the New Diamond was on its way to the Indian port of Paradip
The fire started after an explosion in the boiler room while the New Diamond was on its way to the Indian port of Paradip Sri Lankan Air Force / -

"At this point in time, there are no signs of a leak. Due to the unpredictable situation, however, the above may change and details including ultimate destination and timing are unknown," it added.

Nineteen vessels from India and Sri Lanka have been involved in fighting the fire on the New Diamond, which reportedly started after a boiler room explosion that killed a Filipino crew member on Thursday.

The remaining 22 crew members were rescued.

The vessel was on a journey from Kuwait to the Indian port of Paradip.

"As a result of the incessant effort of the (rescue) mission partners, the flames have been reduced to a certain extent as of now," the Sri Lankan navy said in a statement.

Sri Lanka's Marine Environment Protection Agency (MEPA) is due to visit the area to test water samples for any pollution, officials said.

MEPA has said that legal action could be taken against the owners, Liberian-registered Porto Emporios Shipping Inc, "should the worst happen and the ship breaks up".

The New Diamond is much larger than the Japanese bulk carrier MV Wakashio, which crashed into a reef in Mauritius in July, leaking more than 1,000 tonnes of oil into the island nation's pristine waters.

India