"Biodiversity is being lost at an unprecedented rate," UN Secretary General Ban Ki-moon said in a statement. Global warming is adding to threats such as land clearance for farms or cities, pollution and rising human populations.

"The global response to these challenges needs to move much more rapidly, and with more determination at all levels -- global, national and local," he said.

Many experts reckon the world will fail to meet the goal set by world leaders at an Earth Summit in 2002 of a "significant reduction" by 2010 in the rate of species losses. "We are indeed experiencing the greatest wave of extinctions since the disappearance of the dinosaurs," said Ahmed Djoghlaf, head of the UN Convention on Biological Diversity. Dinosaurs vanished 65 million years ago, perhaps after a meteorite struck.

"Extinction rates are rising by a factor of up to 1,000 above natural rates. Every hour, three species disappear. Every day, up to 150 species are lost. Every year, between 18,000 and 55,000 species become extinct," he said.

"The cause: human activities."

DODO

A "Red List" of endangered species, however, lists only 784 species driven to extinction since 1500 -- ranging from the dodo bird of Mauritius to the golden toad of Costa Rica.

Craig Hilton-Taylor, manager of the list compiled by the World Conservation Union grouping 83 governments as well as scientists and environmental organisations, said the hugely varying figures might both be right, in their way.

"The UN figures are based on loss of habitats, estimates of how many species lived there and so will have been lost," he told Reuters. "Ours are more empirical -- those species we knew were there but cannot find."

UN climate experts say global warming, blamed mainly on human use of fossil fuels, will wreck habitats by drying out the Amazon rainforest, for instance, or by melting polar ice.

The World Conservation Union also said that one in every six land mammals in Europe was under threat of extinction, including the Iberian lynx, Arctic fox and the Mediterranean monk seal.

"The results of the report highlight the challenge we currently face to halt the loss of biodiversity by 2010," European Commissioner Stavros Dimas said.

Europe's goal is to halt biodiversity loss by 2010, tougher than the global target of slowing losses.

Another report by a group of farm researchers said that global warming may drive many wild varieties of plants such as potatoes and peanuts to extinction by mid-century, wiping out traits that might help modern crops resist pests or disease.

The WWF conservation group and the Whale and Dolphin Conservation Society said that whales, dolphins and porpoises were "facing increasing threats from climate change" because of factors such as rising sea temperatures.