More than 5,000 scientists, conservationists and politicians meet in Thailand over the next week to hammer out a blueprint for saving some of the world's most endangered species and fragile ecosystems.

The IUCN World Conservation Union, which is hosting the four-yearly World Conservation Congress, is billing the eight-day Bangkok convention as the one of biggest environmental meetings in history.

"This sends a very powerful message that conservation is not a marginal issue in the year 2004," said Achim Steiner, director-general of the Geneva-based organization. "There has been a record level of interest."

One of the gathering's top events will be the unveiling of the IUCN's "Red List" of endangered animals, the most comprehensive scientific assessment of species at risk of dying out, and concrete measures to slow or reverse their extinction.

The prognosis is not good.

"Despite all our efforts in the conservation community and in governments, we have not really succeeded in stemming the loss of species," Steiner told Reuters.

"The number has now risen to over 15,000 threatened species on our planet -- and this is just the number we have been able to assess so far."

Threats to the environment from rapid economic and population growth -- a major issue in Asia, home to half of humanity -- will also feature prominently at the forum, which includes names from the world of big business.

Oil giants BP and Royal Dutch/Shell, mining conglomerate Rio Tinto and insurer Swiss Re are among multinationals putting in an appearance, reflecting the growing prominence of green issues in the boardroom.

"There has definitely been a shift in the big corporations, who now realize the importance of biodiversity," said IUCN spokesman Deric Quaile. "Most of big business now incorporates this as part of their strategic planning."

ONLY ONE WORLD

The theme of the Bangkok meeting, which opens Wednesday, is "People and Nature -- only one world," to emphasize that conservation and the environment should not be at the expense of human development, and vice versa. Founded in 1948, the IUCN is the world's largest conservation organization, bringing together more than 80 governments, over 800 non-governmental organizations (NGOs) and 10,000 scientists and experts from 180 countries.

It says its unique "union" structure adds to its effectiveness because it bridges the public and private sectors.

At the last Congress, held in the Jordanian capital Amman in 2000, environmentalists said a lack of political will was hampering efforts to preserve threatened species and ecosystems such as coral reefs.

Given the continued decline visible in the past four years, the time for talking was over, they said.

"What we are documenting today is an extraordinary loss of wealth, not only in biological terms, but also in historical terms and in financial terms," Steiner said.

"Every day that passes when we do not take the threat of losing species more seriously will cost us more and more."