Fishing and oil drilling could be banned across more than two million square kilometres of the frigid seas around Antarctica in a historic attempt to conserve the last pristine ocean.

Negotiations this week at a meeting of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) will centre on a proposal for a 1.25m square kilometre "no take" zone, which would cover much of the Ross Sea. Another proposal would establish several other smaller protected areas in the seas around East Antarctica, adding a further 1.9m sq km protection zone. A third reserve, proposed by Germany and backed by Britain, would bar fishing from a large portion of the Weddell Sea, which is the site of the British Antarctic Survey's research station, and where Ernest Shackleton's ship Endurance was crushed by ice in 1915.

The prize, says a coalition of 30 conservation groups including Greenpeace and WWF, is the long-term protection of the nutrient-rich seas around the continent, which are home to more than 10,000 unique species – including most of the world's penguins, whales, seabirds, squid and Antarctic toothfish. The seas are also full of krill, the minute shrimp-like creatures that eat algae and plankton and are the main food for whales, penguins, seals, albatrosses and petrels, but are also increasingly used as feed for fish farms and health supplements.

According to some scientists, the two proposed marine protection areas are vitally important because they support a high percentage of all marine life. At the moment just 1% of the world's oceans is protected, with the result that most of the world's fishing grounds have been significantly depleted.

Countries have committed by global agreement to protect 10% of the world's oceans by 2020, but the creation of the marine protection areas in Antarctica is proving tortuous because it depends on the complex geopolitical interests of the 24 countries, including Britain, the US, Russia, China, Argentina and Chile, all of which have political or financial interest in the waters and the landmass. Russia, Norway and China could yet scupper the conservation plans.

Prospects for agreement on the proposed Ross Sea protection zone looked good until Russia and Ukraine questioned the legal basis of the commission's plan. As part of a compromise, New Zealand and the US have now proposed a 40% smaller area to try to keep Russia aboard. All decisions by the commission must be made by consensus.

Norway, which portrays itself as one of the world's most environmentally responsible nations, is believed to have deep reservations about the zones, because they could limit its fishing fleet, which already catches vast quantities of krill off the coast of Antarctica to feed large salmon farms back home.

Norwegian spokeswoman Kristin Enstad said last night: "Norway supports the establishing of marine protected areas in Antarctica. It is essential that marine-protected area plans are scientifically well-founded and practically feasible. Norway will work actively to ensure that the commission agrees on marine-protected areas in the Ross Sea.

"In the case of East Antarctica, Norway is positive to continuing the efforts to establish marine protected areas also here. The specific proposal now on the table is however not sufficiently advanced for Norway to be able to consider it now." Other countries, including China and Japan, have queried the science and the size of the proposed reserves and demanded the inclusion of a "sunset clause", which meant the decision could be reviewed in the future. The level of protection in all the areas will be hotly contested.

But conservation groups say they are cautiously optimistic, believing countries know this is the best chance in years to protect sea on a large scale. "More than one million people around the world have joined the global call for large-scale marine protection in Antarctica," said Jim Barnes, director of the Antarctic and Southern Coalition of 30 environment groups. "Agreeing on large marine protected areas in the Ross Sea and East Antarctica is a key test of whether countries honour their international commitments. The science supporting the two proposals is compelling, and it is only short-term economic gain that is blocking consensus," he said.

There are more than 5,800 marine protection areas, but most of these are small and fragmented. The Chagos Archipelago in the Indian Ocean was declared the world's largest marine reserve in April 2010 with an area of 640,000 sq kilometres.