Both New Zealand and Australia are asking their ambassadors to express concern to the South Korean government about its plan to start whaling.
New Zealand's Foreign Minister Murray McCully says whales in the North West Pacific are already heavily targeted by Japan and large numbers are also caught as by-catch by Korea.
Mr McCully says scientific whaling is commercial whaling in drag and Korea's plan would be a serious setback for whale conservation.
Meanwhile Australian Prime Minster Julia Gillard says she is very disappointed by South Korea's announcement.
We are completely opposed to whaling," she said.
"There's no excuse for scientific whaling, and I have instructed our ambassador in South Korea to raise this matter today at the highest levels of the Korean government."
The Green Party is also condemning South Korea's plan to start whaling under a loophole in the whaling convention that allows it for scientific purposes.
Greens' co-leader Metiria Turei says the loophole in the international whaling convention needs to be closed.
South Korea's delegation at the International Whaling Commission, meeting in Panama, said it wanted to reinstate traditional whaling.
It said minke whales are eating large amounts of fish stocks and sight-surveys of the whales are not providing enough information on their feeding habits and the fisheries resource.
The South Korean delegation said its government is considering whaling to get the data.
Delegation leader Joon-Suk Kang said the proposal was not finalised, and that whaling would not begin until plans had been discussed by an international group of expert scientists convened by the IWC, the BBC reports.
The proposal was strongly condemned by anti-whaling governments at the commission, including New Zealand.
New Zealand delegation head Gerard van Bohemen said scientific whaling of a group of minke whales in the region, known as J-stock, borders on the reckless.
Hunting would take place near the Korean coast on minke whales but how many would be caught is unclear, the BBC says.
Any government is entitled under the International Convention for the Regulation of Whaling (ICRW) to embark unilaterally on a scientific hunting programme, although Japan is the only one that currently does so.