China is threatened by more than 400 invasive alien species, which has caused billions of yuan of economic losses, an agricultural official said Monday.

"We have discovered more than 400 harmful species alien to the country so far," said Wan Fanghao, vice director with the Research Center for Invasive Alien Species Prevention and Control of China's Ministry of Agriculture. "More than 100 of them are widely spread in the country and have caused great losses."

Wan made the remarks while attending the ongoing International Congress on Biological Invasion in the southeastern Fujian Province.

More than 500 experts from 50 countries and regions around the globe are attending the congress to address the threats of invasive alien species.

Wan warned that the situation in China was very severe. "Due to these invasive alien species, China is now suffering a direct economic losses of at least 50 billion yuan (7.3 billion U.S. dollars) while the total economic losses are about 130 billion."

Statistics showed that more than half of the 100 dangerous alien species listed by the World Conservation Union (IUCN) have been found in China.

An alien species, when invading a new environment without being monitored, is apt to proliferate and form a mono-dominant community, competing for living spaces previously enjoyed by local species.

"They are ruining bio-diversity, threatening the ecological system and driving local species to extinction," Wan said.

Chen Wanquan, vice head of the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences, said China has invested millions of dollars in tackling invasive alien species.

But risks are growing along with the expanding global trade.

At the congress, scientists urged the international community to work together to defuse the threat of the invasive alien species.

"No country can do it on its own," said Dennis Rangi, Executive Director of CAB International (CABI), formerly known as the Commonwealth Agricultural Bureau.

"It's going to be done at the global level, to make sure that we are working as a team dealing with the new species," he said. (Xinhua)