When he is not on his farm in the high country of south-east New South Wales, Hans Berekoven is an amateur marine archaeologist recovering artefacts from a shipwreck for a Malaysian museum.

He said during one trip, he had been harassed by a Chinese Coast Guard vessel that had been stationed off Luconia Shoals for the past few years.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 3 minutes 21 seconds 3 m 21 s Professor Clive Schofield talks about the overlapping claims between Malaysia and China ( Bill Brown ) Download 3.1 MB

The shoals are a cluster of reefs and a tiny island called the Luconia Breakers, 84 nautical miles off Malaysia's Borneo coast.

"They were trying to push us out. When we arrived there and started diving, they would up-anchor and sort of circle around us, sometimes really close. It was a sort of gentle intimidation," Mr Berekoven said.

China, Taiwan, the Philippines, Indonesia, Malaysia and Brunei all have competing claims over the South China Sea.

The dispute has been a major flashpoint in the region, with accusations of China building artificial islands and damaging reef systems.

An international tribunal recently ruled China had violated the Philippines' economic and sovereign rights as defined by the United Nations Law of the Sea Convention.

The Luconia Shoals are about 84 nautical miles off Malaysia's Borneo coast. ( ABC News )

Since 1947, China has claimed a vast area of islands in the South China Sea, including the Luconia Shoals.

Professor Clive Schofield, an authority on marine jurisdictional issues, said that at 84 nautical miles from the Borneo coast, the Luconia Shoals were clearly on Malaysia's continental shelf, and well within Malaysia's 200 nautical mile exclusive economic zone (EEZ), as defined by the Law of the Sea Convention.

"So if there's any jurisdiction and rights over the feature [the Luconia Shoals], then they are Malaysian and not Chinese," Professor Schofield said.

Mr Berekoven said he was angered by damage he alleged was being caused by the China Coast Guard vessel anchoring on the reef.

"She's got a massive anchor chain. Every time the wind changes or the current changes that big anchor chain is just making a hell of a mess of that reef," he said.

Hans Berekoven (centre) and Malaysian colleagues with Malaysian flag on Luconia Shoals. ( Supplied: Hans Berekoven )

Mr Berekoven chose Malaysia's independence day, August 31 last year, to protest against the situation by raising the Malaysian flag on the tiny island.

It is the first time the video of the incident has been released.

"I took the curator of the museum that we're working with, and a couple of other Malaysian friends, and a journalist from the Borneo Post," he said.

They mounted a stainless steel flagpole into a cement footing and raised the Malaysian flag, as the China Coast Guard vessel watched from about 500m offshore.

"They must have got on the blower to Beijing and Beijing must have got on the blower to Kuala Lumpur, because suddenly there was a big kerfuffle in KL," Mr Berekoven said.

The next morning, a Malaysian aircraft flew low over Mr Berekoven's boat and the island.

"A Malaysian coast guard vessel was despatched. Went out there and unbolted the flag," he said.

"It's absolutely absurd. It's 88 miles, well within the 200 mile economic exclusion zone, and they've forced the Malaysians to take the flag down — their flag, asserting their authority, their sovereignty."

Professor Schofield said he was not surprised at Malaysia's action, because Malaysia had traditionally dealt with issues by taking a quiet diplomatic route with China and avoiding public conflict.

Tensions over oil, gas and fisheries rights

He said tensions in the South China Sea focused on the wealth of oil and gas resources in the region, and freedom of navigation in the busy maritime trade routes.

"However, the importance of the fisheries is often overlooked," Professor Schofield said.

"The South China Sea has been estimated to provide around 12 per cent of global fisheries catch.

The view from Hans Berekoven's dive boat of the Luconia Breakers, with a China Coast Guard ship visible on the far side of the tiny island. ( Supplied: Hans Berekoven )

"It provides fisheries which are vital to food security within the region, where potentially hundreds of millions of people have their primary protein requirements met by the fish from these waters."

Professor Schofield said a rare exception to Malaysia's quiet diplomacy with China occurred earlier this year when about 100 Chinese fishing boats arrived at the Luconia Shoals.

"For Malaysia there was a relatively strong reaction calling in the Chinese ambassador to protest against that," he said.

Malaysia's national security minister Shahidan Kassim was reported by the Bernama news agency as announcing the despatch of assets from the Malaysian Maritime Enforcement Agency, and that the navy had been sent to the area near the Luconia Shoals to monitor the situation.

Professor Schofield said such an action underlined the importance of the fishery to Malaysia.

He said fisheries in the region were over-fished and under extreme stress with fish stocks declining.

"You have overlapping claims and rival fisheries fleets and no unified or rational management of those stocks. The potential for a collapse in the fisheries is a real and present one," he said.

Mr Berekoven is preparing to return to Luconia Shoals to resume recovering artefacts from the nearby shipwreck.