South Korea came under pressure on Thursday from outraged governments and environmentalists to scrap plans to kill whales under a 'scientific' research programme denounced as a sham.

Critics of Seoul's decision, announced on Wednesday at an International Whaling Commission (IWC) meeting in Panama, said so-called scientific whale catches were just an excuse for commercial whaling.

An IWC moratorium on whaling introduced in 1986 permits lethal research on whales, with the meat then allowed to be used for consumption. This loophole is already widely used by Japan.

Australia and New Zealand told their ambassadors to raise concerns with Seoul.

"I'm very disappointed by this announcement by South Korea. We are completely opposed to whaling, there's no excuse for scientific whaling," Australia's Prime Minister Julia Gillard told reporters.

New Zealand's Foreign Minister Murray McCully said there was no need to harpoon whales to conduct effective research.

"(It) will have no more credibility than the so-called scientific programme conducted by Japan, which has long been recognised as commercial whaling in drag," he said.

And the country's Prime Minister John Key, speaking during a visit to Sydney, called the move 'a terrible step in the wrong direction' for South Korea.

Greenpeace described scientific whaling as 'just thinly disguised commercial whaling'.

"This is the 21st century, and it has been proven time and time again that we don't need to kill whales to study them," it said in a statement.

Seoul's move appeared to come as a shock to opponents both at home and abroad.

"We were taken by surprise by this decision. Our office is being flooded by phone calls from campaigners abroad, including those in New Zealand, Britain and Australia," Greenpeace Korea marine campaigner Han Jeong-Hee told.

South Korea's chief envoy to the IWC meeting, Kang Joon-Suk, said consumption of whale meat 'dates back to historical times' in his country and the minke whale population had recovered since 1986.

Seoul said it would announce later how many whales it would kill and when in its own waters, but insisted that it did not need foreign approval.

Greenpeace disputed claims that the minke whale population had recovered but said Seoul's whaling programme could not start right away.

It must be reviewed by an IWC scientific committee and Seoul seemed unlikely to ask for this review before next summer, its statement said.

The Korean Federation for Environment Movement (KFEM) urged the government immediately to withdraw its plan.

"We condemn the agriculture and fisheries ministry for following Japan's lead in hunting whales, which has become the object of international criticism," it said in a statement.

The federation said the ministry, which considers all whales "not as endangered mammals but as fish to be captured", should be stripped of its power to make decisions on whaling.

Whalemeat is traditionally popular in and around the southeastern coastal city of Ulsan. South Korea already allows the sale of meat from whales said to have been accidentally caught in nets.

But the country's unusually high rate of 'bycatch' has raised suspicions among activists that they are sometimes deliberately killed.

Some 100 whales, most of them minke, are netted accidentally every year in South Korean waters, Sohn Hawsun, a researcher at the National Fisheries Research and Development Institute, told AFP.

KFEM called on the government to ban trade in whalemeat and encourage fishermen to release whales by paying compensation.

Greenpeace said the country also has 'a large and profitable illegal hunt of whales and every year there is fresh evidence of this continuing problem'.