China Tuesday called allegations that it bought US military space technology from a Chinese-born physicist a complete fabrication made with ulterior motives.

"This so-called report about China stealing outer space technology from the United States is a sheer fabrication made out of ulterior motives that is doomed to failure," foreign ministry spokesman Qin Gang told journalists.

Qin refused further comment. China routinely denies allegations that it is involved in espionage against other nations.

On Monday, Chinese-born physicist Shu Quan-Sheng pleaded guilty before a US court to illegally exporting American military space know-how to China, the US Justice Department said.

Shu, a naturalised US citizen, admitted handing over to Beijing information on the design and development of a fueling system for space launch vehicles between 2003 and 2007, the department said in a statement.

Shu, 68, pleaded guilty to violating the Arms Export Control Act by helping Chinese officials based at the space facility on southern Hainan island to develop manned space flight and future missions to the moon.

He also acknowledged he had sent them in December 2003 a specific military document detailing the design of liquid hydrogen tanks crucial to launching vehicles into space, it said.

Shu, who is the head of a high-tech company, AMAC International, with offices in Beijing, admitted a third charge of bribing Chinese officials to the tune of some 189,300 dollars.