Paris: China faces damage "on a potentially huge scale" from introduced species, a threat that is being amplified by preparations for the Beijing Olympics, scientists warned today.

Hundreds of species of animals, plants and insects have been brought into China since the country opened its economy in the early 1990s, they said in a study. At least 400 newly-introduced species can be categorised as invasive, stealthily spreading into new habitats and displacing native species and inflicting an estimated annual economic cost of some 14.5 billion dollars.

Some of them are already well established locally but are now swiftly spreading further afield through the country's transport and water distribution networks. The study, written by Chinese and American researchers, appears in BioScience, a US journal. It singles out water hyacinth (Eichhornia crassipes) as a special pest.

Along with alligator weed (Alternanthera philoxeroides) and water lettuce (Pistia stratiotes), water hyacinth was among aquatic plants that farmers in southern China were encouraged to grow in the 1960s and 1970s as cheap animal fodder. These plants -- now replaced by more effective animal feed -- have escaped into ponds, rivers and lakes in southern China, "causing much damage to fisheries, irrigation and natural ecosystems in as many as 20 provinces."

China's South-to-North Water Diversion Project, a canal aimed at easing water shortages in northern China, could become an "express route" for distributing the aliens, the paper said.

Source : PTI