The World Conservation Congress opens with the release of the annual red list of threatened species which is expected to paint a gloomy picture of the state of the planet's wildlife.

One in four mammals and one in eight birds are known to be at risk and hundreds more species are expected to be added to the list for this year's edition. Last year's report said 12,259 species were threatened.

More than 5,000 scientists, activists and government representatives are expected to attend the nine-day conference designed to highlight the growing threat to wildlife amid rampaging development in parts of the world.

The congress, organised by the World Conservation Union (IUCN) and bringing together scientists and experts from 181 countries and more than 50 national environment ministers, will debate the escalating extinction crisis and form plans for the next four years.

Only the world summit on sustainable development in 2002 at Johannesburg, a one-off event, was larger, say the organisers.

The release of the red list follows a series of other reports warning of the increasingly troubled state of the world's biodiversity.

A three-year study published last month said one third of the world's amphibians were under threat of extinction, partly blamed on pollution and global warming.

More than 100 amphibian species are feared to have disappeared since 1980 and scientists fear hundreds more will become extinct in coming decades.

The IUCN said half of the world's wetlands have been destroyed in the past century and more than a quarter of the world's coral reefs have also been lost.

However the congress is also expected to reveal success stories of species brought back from the brink by concerted conservation action.

The organisers said the third congress, held every four years, comes amid a growing pressure on governments from people who recognise things need to be done.

"The public is getting seriously worried about the implications and pace that climate change is changing every day life situations," Achim Steiner, IUCN's director general told AFP.

"What we are trying to do is bring conservation and biodiversity issues to the forefront of public attention. We have seen conservation in the last few years lose some of the public attention."

The IUCN congress is the second major conservation conference held in Bangkok in the last two months.

A global wildlife trade meeting in October addressed the threat of extinction through trade and handed greater protection to species including great white sharks and blocked moves by Japan to increase trade in Minke whales.

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