China has experienced an invasion of more than 20 species alien to the country in the past decade and the situation shows signs of worsening, scientists warned on Sunday.

China is one of the countries that suffer most from alien invasive species and has recorded more than 400 such species so far, said Guo Yu Yuan, researcher of the Institute of Plant Protection of Chinese Academy of Agricultural Sciences.

More than half of the 100 dangerous alien species listed by the World Conservation Union (IUCN) has been found in China, said Guo, who is also academician of Chinese Academy of Engineering, at a symposium in Fuzhou, capital of east China's Fujian Province.

The invasion of alien species is on the rise in China with fast-growing foreign trade, and has brought about more and more biological problems, said Xie Lianhui, academician of Chinese Academy of Sciences.

Wan Fanghao, an official with the ministry of agriculture, said some alien species have already caused disasters in the country.

The American White Moth, native to North America and first detected in Northeast China's Liaoning Province in 1979, is threatening forests and crops in 116 counties of six provinces and municipalities in China including Beijing, Tianjin, Hebei and Liaoning, according to the State Forestry Administration (SFA).

The moth denudes a tree, and consumes vegetables and crops in days. It boasts a strong reproduction ability. A female moth can lay some 2,000 eggs in one go, and can breed 30 million to 200 million descendants a year, according to biologists.

It is also reported that water hyacinth is posing a serious problem in rivers, lakes and ponds in south and southeast China's Guangdong and Fujian provinces, southwest China's Yunnan Province, east China's Jiangsu and Zhejiang provinces and in Shanghai.

A total of 32 alien species are causing damage worth 56 billion yuan to China's forestry industry every year, according to Zhu Lieke, vice director of the SFA at a forum in September.

Every year 10.7 million hectares of forest in China are damaged by harmful species and 20 percent of these are damaged by alien species, Zhu said.

A total of 127 scientists from across the countries attended the symposium in Fuzhou and signed a Fuzhou Accord, calling for the establishment of a national society on alien species and enhanced cooperation with foreign counterparts.

(Xinhua News Agency December 10, 2007)