Thousands of whales could be killed legally for the first time in 25 years under new proposals put forward by the International Whaling Commission.
The body, set up to protect the species in international waters, banned the commerical hunting of whales outright in 1986.
But whaling nations like Japan, Norway and Iceland continued to hunt the mammals using a series of loopholes, such as whaling for "scientific research".
The IWC, which is due to meet next month to update the law around the protection of whales, has suggested the only way forward is to set up a series of quotas.
It is argued that this will limit the slaughter because the killing of whales is controlled under international law.
However the details of the proposals reveal that the quotas will be in the thousands and include endangered species. Papers issued by the IWC suggest thousands of minke whales could be killed in the Southern Ocean over the next ten years. Even fin whales and sei whales, that are officially in danger of dying out, are included.
Environmentalists were outraged, arguing that the killing of whales should never be sanctioned under international law while the species is still under threat of extinction.
Heather Sohl, species policy officer for WWF-UK, said it was "ridiculous" to allow hunting of whales in the Southern Ocean, which is a critical feeding ground for species including blue whales.
"Some whales feed exclusively in the Southern Ocean - not eating at all during the winter months when they travel up to tropical waters," she said.
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"Allowing commercial whaling in an area where whales are so vulnerable goes against all logic."
She also criticised the decision to include fin and sei whales in the quota.
"Both fin and sei whale species were depleted to severely low levels by previous whaling that spun out of control, and they remain endangered as a result.
"Allowing new commercial whaling on these species when they have yet to recover from previous whaling is management madness."
Whaling nations like Japan back the IWC proposals and are arguing for even higher quotas.
But critics, including the UK, US and Australia, are against any deal that could cause an increase in whale hunting.
The IWC will meet in in Agadair, Morocco at the end of this month. Nations will decide on whether to set quotas and the catch that will be allowed. There are also proposals to promote whale watching as an alternative source of income for whaling communities and to protect whales from climate change and over fishing.