Most of the sandstorms that have swept China this year originated from foreign land, a Chinese official in charge of desertification control said Monday.

And the invasions can partly explain the frequent occurences of sandstorms in the country in recent years despite its achievements in desertification control.

Liu Tuo, an official with the State Forestry Administration (SFA), made the remarks at a press conference held here on Monday for Beijing International Conference on Women and Desertification.

Since the start of this spring, the north and northwestern Chinese regions have been hit by 17 sandstorms, of which, a dozen came from foreign land, said Liu

The official also reinforced his claim by citing statistics which showed between 2000 and 2004, 29 of 40 sandstorms that hit the northern Chinese regions were "invaders."

Situated in the central-Asia sandstorm region, one of the world's four largest sandstorm sources, China also falls prey to legions of sandstorms from outside the country while being blamed as a sand source to northeast Asia, Liu noted.

The other three major sources are in Africa, North America and Australia.

The land suffering from desertification has been decreasing by 7,585 sq km annually in China, and the area of sandy land has also been falling by 1,284 sq km a year, Zhu Lieke, SFA deputy director said at the same press conference.

The shrinkage poses a stark contrast to the fact that the land suffering from desertification and sandy feature were added by 10,400 sq km and 3,436 sq km late last century, respectively.

Currently, the desertification land in China makes up 2.64 million sq km, accounting for 27.46 percent of the nation's territory, and its sandy land totals 1.74 million sq km, accounting for 18.1 percent of the country's total