Watson defended the action, arguing that krill trawlers are depleting feeding grounds used by humpback and fin whales, penguins, seals, and seabirds.

But Aker Qrill, which owns the trawler said the action constituted a criminal act under international law and it would pursue legal proceedings -- prompting Watson to compare the company to "frightened drama queens".

The incident occurred on March 31, when the MV Bandero, operated by the Paul Watson Foundation and Sea Shepherd France, "deliberately rammed Aker Qrill company's fishing vessel," Aker Qrill said in a statement.

"The point of impact was directly above a diesel fuel tank. The (vessel) Antarctic Sea was operating many days away from the nearest port or rescue capability. The crew was not injured but was put in danger in these waters, where margins matter," it added.

The company said that had the vessel been heavily damaged, "people and the environment would have been at risk due to the approaching severe weather."

Aker Qrill said it was taking legal action, noting that "ramming a vessel in international waters is a criminal act".

"This is the direct result of campaigns built on false information, creating a climate where confrontation replaces dialogue," Aker Qrill chief executive Webjorn Barstad said.

In a separate statement, Watson confirmed the altercation and called for an end to krill trawling in Antarctica.

"Aker is trying to portray themselves as innocent victims while engaged in starving whales and penguins," he said.

"We scratched their paint and they reacted like frightened drama queens, in response to our message to cease and desist from causing further damage to the fragile eco-system of the Southern Ocean."

"Ecocide is terrorism and we oppose ecoterrorism with non-violent tactics to defend life in the sea from the greed of this voracious industrial enterprise."

Aker Krill meanwhile argued that the organisation's claims were "not supported by any scientific picture", and said it operated under the oversight of CCAMLR, the 27-nation body that governs Antarctic fisheries.

Watson, who featured in the reality TV series "Whale Wars", founded the campaign group Sea Shepherd and the Captain Paul Watson Foundation (CPWF).

Adept at gaining publicity, he has gained notoriety for "direct-action" tactics such as ramming vessels and using acoustic weapons, water cannon and stink bombs.