Japan agreed to release the two activists that were detained on Tuesday on board of the Japanese whaling ship only if the Sea Shepherd will stop pursuing them.

The activists, Australian Benjamin Potts and Briton Giles Lane, came on board of Yushin Maru 2 to tell whalers that is illegal to hunt along the coastline of Australia.

They were accused by the Japenese whalers for attacking the vessel with bottles of acid, the Associated Press reports.

Sea Shepherd President Paul Watson said that Japanese whalers’ demands are “terrorist” tactics and that he would not agree with them.

He said: "When you start making demands for the return of hostages that sounds like terrorism to me," AFP quotes.

Japan said that it wants for the men to be released, but is waiting Sea Shepherd’s response to the proposition.

Japanese government spokesman Nobutaka Machimura said: "The ship has been sending messages to hand the two individuals back to Sea Shepherd. But so far the group has not responded."

He continued: "I do not believe this will affect diplomatic relations, but their actions are very dangerous and interfere with legal activities conducted in the public ocean. The Japanese government strongly condemns these acts," he said.

According to Australian Foreign Minister Stephen Smith, Japan agreed to free the men after it was contacted by Australian officials later Tuesday.

He said that right now the safety of the men comes first and that the Australian government wishes for them to be released immediately.

According to the Sea Shepherd, the two activists were tied to the radar mast of the harpoon ship.

Those accusations were denied by a spokesman for Japan's Institute for Cetacean Research. According to his sayings they were given hot meals, a bed and a bat.

Glenn Inwood said that their were detained on the deck for a period of time before their were taken to an office

“It was the only way, you couldn't have them running around the deck not knowing what they're going to do," he said.

Minoru Morimoto, director of the institute, said that the two tried to wrap up ropes to the ship’s propeller and threw bottles with acid on the deck.

Hideki Moronuki, head of Japan's Fisheries Agency said that in the past Japanese whalers had been attacked by Greenpeace and Sea Shepherd.

Moronuki said: "We want to make sure they will not, for example, ram their ships against the Japanese ship when it stops to drop the individuals. The individuals are kept in an office of the ship, kept warm and safe."