The activist group will leave South Africa in two ships within the next few days to search the vast Southern Ocean to confront the whalers and stop the hunt, he said.

A six-ship Japanese fleet left for the Antarctic last week and plan to double its target catch, spearing more than 900 minke whales, and 10 fin whales -- an endangered species second in size only to the blue whale.

Tokyo maintains that whale meat is an important part of its culinary tradition, but anti-whaling nations and environmental groups condemn as cruel and unnecessary the practice of hunting the giant marine mammals.

Rattenbury said uncontrolled commercial whaling over the past century had wiped out 90 percent of the planet's whales, and has brought many species to the brink of extinction.

"We are facing a growing wave of ocean extinction, our seas have reached a tipping point with scores of species of fish, birds and mammals edging towards extinction," he said.

The planned confrontation is the first phase of a 14-month campaign that will see Greenpeace vessels sail the world to gather research and drum up support for a campaign to declare 40 percent of the world's oceans protected areas.

Japan abandoned commercial whaling in 1986 in line with an international moratorium and began what it calls a research programme the following year, but meat still ends up on plates in restaurants.

The International Whaling Commission passed a non-binding resolution at a meeting in June that urged Japan to scrap research whaling altogether, while Japan lobbied for commercial whaling to be allowed again.