A group of foreign conservation volunteers sailing off the coast of Kep province late on Friday night were set upon by a flotilla of illegal fishermen who attempted to pelt them with rocks and other projectiles, only disbanding after Cambodian maritime police fired warning shots into the sea.

According to Paul Ferber, founder of Marine Conservation Cambodia (MCC), an oceanic research group that also monitors illegal fishing in Kep Bay, the incident occurred while a boat of seven foreign, mostly young volunteers were out on the bay for a stargazing cruise after 10pm.

Ferber said that when the stargazers unexpectedly encountered an illegal trawler about 1 kilometre off of Koh Seh, MCC’s research island near the Vietnamese border, the fishermen cut their trawling nets – which were electrified, added Ferber, “a class-one jailable offence” – and began chasing the volunteers.

As the volunteers fled towards Koh Seh, seven more trawling vessels appeared and joined in the pursuit. Nearing Koh Seh, three pursuing fishing boats began hurling rocks, tools and even squid at the frightened foreigners, according to volunteers present.

“It was like a pack of hyenas attacking water buffalo. Pretty scary,” said Australian volunteer Carney Miller, 21, in an interview yesterday.

When the volunteers reached Koh Seh, they were met by Ferber in another MCC boat, which had picked up two armed Cambodian marine police officers from their cantonment on the other side of Koh Seh. While attempting to reach the volunteers, Ferber’s boat was rammed head-on by a trawler.

“If our captain had not manoeuvred quickly, it would’ve hit us directly in the side, sinking us,” said Ferber.

When the fishermen came in for a second ramming, one of the officers on board fired his AK-47 into the bay as a warning, which successfully dispersed the aggressive trawlers who fled back into the bay, said Ferber.

As that was happening, three trawlers destroyed MCC’s third and smallest vessel, which was unmanned and moored by their pier, by repeatedly ramming it. One volunteer said he also witnessed fishermen lobbing lit petrol bombs at the boat, which missed their mark and fizzled in the sea.

Ferber, whose group has monitored illegal fishing in Kep Bay for four years, said that the incident marked a dramatic escalation in the effort against illegal fishing there.

The Briton speculated that the trawler’s heightened aggression might be due to an intensified government crackdown on the trawlers. In the first nine months of 2015, illegal fishing busts were up 150 per cent compared to the same period the previous year, according to the Ministry of Agriculture, Forestry and Fisheries.

Tep Yuthy, deputy governor of Kep, said that teams from the marine police and fisheries administration were conducting an investigation into the incident, though he had not received any findings of the investigation, he said.

Kuch Virak, director of the recently inaugurated Kep fisheries office, confirmed the investigation.

“We have some leads but we cannot provide any information because it is an ongoing investigation,” he said.

Additional reporting by Niem Chheng and Mech Dara