UNESCO, whose World Heritage Committee is holding its annual meeting in Vilnius, Lithuania, said in a statement that the committee had considered petitions from environmental groups to place the world's tallest peak on its endangered list.

However UNESCO decided not to do so. UNESCO spokeswoman Gina Doubleday said while the effects of climate change on Everest were noticeable, more study and discussion needed to be done.

"It just doesn't happen like that. There's a whole procedure for putting a site on the endangered list," she said. "It has to be discussed and documented," she added.

Mount Everest could go on the list at a later date, she said, but would not speculate on when.

Environmental groups, such as Friends of the Earth, have called on the UN cultural body to act because they say global warming is melting the glaciers surrounding Mount Everest.

If UNESCO placed Everest and other sites on its protection list it would force governments to act to protect them.

"We are extremely angry that the World Heritage Committee has not taken any meaningful action to protect some of the most important sites on the earth from climate change," said Peter Roderick of the pressure group Climate Justice Programme.

"The dangers are clear and the main cause of the problem is known," he said.

As well as Nepal's Everest National Park, campaigners say the glaciers in the Huascaran National Park in the Peruvian Andes are melting fast while the Belize Barrier Reef is threatened by rising sea temperatures that is killing off coral.

Friends of the Earth said UNESCO had been urged by an international coalition of lawyers and environmentalists to take urgent action to protect Mount Everest.