A new fire broke out on a supertanker carrying about 2 million barrels of oil in the Indian Ocean off the east coast of Sri Lanka, spokesmen for the country's navy said on Thursday, adding that one of its 23 crew was missing and another injured.

Navy spokesman Captain Indika de Silva said flames had spread to the bridge of the New Diamond, and that two Russian warships in Sri Lanka's Hambantota harbour had left to assist in the firefighting. He had earlier said navy personnel at the scene had reported the fire was under control.We will need an international effort," de Silva said, adding that there was still no damage to the ship's cargo area.

"There were 23 crew on board. We are bringing one injured crew member to Sri Lanka on board one of our vessels."

The New Diamond, a very large crude carrier (VLCC) chartered by Indian Oil Corp (IOC), was fully loaded with the equivalent of about 2 million barrels of oil, Refinitiv data showed.

Photographs taken by Sri Lanka's air force showed extensive damage to the tanker's funnel, and thick black smoke and flames coming from the bridge, that sits just behind the cargo area.

Another spokesman, Commander Ranjith Rajapaksa, said the VLCC was ablaze about 20 nautical miles off the east coast of Sri Lanka and that the military had sent an aircraft and two ships to assist.

One of its 23 crew was missing, Rajapaksa told Reuters.