ALMOST a third of the world's frogs, toads, newts and other amphibians face the threat of extinction, a major global study has revealed.

The discovery is seen by experts as a possible early warning of environmental disaster.

Amphibians act like canaries in a coal mine because their highly permeable skin makes them so sensitive to the effects of climate change and pollution. Russell Mittermeir, president of Conservation International, which co-led the new research, said: "Their catastrophic decline serves as a warning that we are in a period of significant environmental degradation."