The incident took place in Malaysian waters, where local fishermen have complained in the past about Vietnamese fishing boats damaging their nets.

MMEA chief Zubil Mat Som told AFP that two Vietnamese fishing boats had entered Malaysian waters some 80 nautical miles from Tok Bali, off Kelantan, on Sunday.

“The coast guard crew had earlier fired warning shots in the air but after the Vietnamese boats rammed and threw a bottle of petrol, my men had no choice but to open fire in self-defence,” he said.

Zubil alleged the Vietnamese crew had thrown petrol and a tyre to try and set fire to the MMEA boat, which was damaged by the “aggressive ramming”.

A Vietnamese fisherman suffered gunshot wounds and was pronounced dead after he was brought to shore.

“We are saddened by this incident. But I can guarantee that my men took this action to protect their lives and our national sovereignty,” said Zubil.

The Vietnamese boats with the remaining 20 crew members were towed to the MMEA jetty.

Parts of the South China Sea are subject to rival claims by Brunei, Malaysia, the Philippines, Taiwan and Vietnam while Beijing claims the entire waterway.

The rival claims to the sea, which straddles vital shipping lanes and covers rich fishing grounds, make it a potential flashpoint for conflict.

China and Asean – where four claimants are members of – are currently in talks for a code of conduct in the area.

While not a claimant, the US has been sending “freedom of navigation” patrols to international waters, but China has slammed these as interference in regional affairs.

In February, Putrajaya sought to secure a deal with Hanoi to end alleged intrusions into Malaysian waters by Vietnamese vessels.