"Norway would be the first country in the world to take on such a concrete commitment," Stoltenberg said in a proposal to his Labour Party that was met by a standing ovation.

Many Norwegians are worried about climate change even though the economy relies heavily on earnings from oil and gas. Burning fossil fuels is widely blamed as a main cause of global warming.

"The greenhouse effect...is our most dangerous environmental problem," Stoltenberg said in his speech, listing risks such as thawing of Siberian permafrost, death of the Amazon rainforest or a spread of the Sahara.

Under the 2050 plan, domestic emissions would be offset by cuts abroad or by buying emissions quotas on international markets. Norway could, for instance, help China or India to shift to solar or wind power from burning coal or oil.

CABINET BACKING

Stoltenberg said his proposals already had backing from his three-party centre-left cabinet, which has a majority in parliament. "I feel sure it will be adopted" by the party, he told reporters. Norway would also unilaterally sharpen its commitments under the UN's Kyoto Protocol for fighting climate change to 2012 and cut emissions by 30 percent by 2020, a tougher goal than set by the European Union.

The EU says it will cut unilaterally by 20 percent by 2020 and by 30 percent if others make similar cuts. Among other tough goals, California aims to cut emissions by 80 percent by 2050, by which time Iceland aims to phase out use of oil.

Norway would tighten its Kyoto goal by 10 percentage points, Stoltenberg said. Kyoto obliges Norway to limit a rise in emissions to one percent above 1990 levels by 2008-12.

Stoltenberg did not say how emissions cuts would be spread between cuts at home or measures abroad.

Environmental pressure group Greenpeace said that Norway should do more at home rather than use its vast oil wealth to buy its way out of the problem.

Norway has savings from oil of US$300 billion.

"Norway wants to be a driving force in seeking a new binding climate agreement," Stoltenberg said, adding that all countries, including Kyoto outsiders like the United States and developing nations, should join in extending Kyoto beyond 2012.

Emissions of greenhouse gases by Norway were 8.5 percent above 1990 levels in 2005 at 54 million tonnes, boosted by emissions from offshore oil and gas platforms. Emissions per capita are about 11 tonnes, almost three times the world average.