Whale hunting for commercial use has been banned since 1986, but Japan continues to slaughter up to 1000 animals a year for what it insists are research purposes. Attracting worldwide criticism, whalers are a popular target for animal rights activists. Yesterday a group that has been hounding Japan’s Institute of Cetacean Research threw butyric acid (rotten butter) and Methocel (a slippery liquid normally used to coat tablets) on to the vessel’s deck. Three crew members say they were injured in the attack. The activists however refuse to give up. They say their work has prevented the ship from killing any whales for four and half weeks. But what happens next will depend on delegates from the International Whaling Commission, who are meeting in London to discuss the controversy this week.

The video was filmed by Japan's Institute of Cetacean Research, who capture the whales, on Sunday 2 March. They describe the Sea Shepherd mission as a "self-righteous terrorist group" and called the attack "illegal harassment and terrorism", saying that:

"The SSCS vessel crews threw more than 100 bottles of butyric acid and slippery substances to the Japanese whaling vessel Nisshin Maru. Three Japanese crews were injured (their eyes and so on)."

The ship plays a recorded message to their attackers: "Warning, warning, this is the Nisshin Maru captain. Stop your destructive actions immediately. If you dare to board this vessel you will be taken into custody and restrained as illegal intruders under Japanese law."

"All we’re doing is throwing stink-bombs!"

Captain Paul Watson of the Sea Shepherd vessel, named Steve Irwin, spoke to us using an onboard satellite phone:

Our objective is to keep their decks so smelly and slippery that nobody can work on them. And we only use organic, non-toxic materials to do it. We're feeling pretty good onboard; we know we're going to have saved 500 whales. They're not going to kill any today, and not tomorrow either. In about two weeks conditions will change and they won't be able to continue [hunting], and we're going to chase them right to the end.

Everyone knows it's not for research. They haven't produced one paper on their findings since 1986! But whale meat is still sold and still eaten. It's a question of pride. No-one's going to tell Japan what to do. They're violating an Australian court order and international laws. These guys are poachers, criminals, and they're getting away with it. If you poach elephants in Africa you'll be shot dead. All we do is throw is stink-bombs!"