With relations between the US and China severely strained over the bombing of the embassy in Belgrade, further details are emerging of alleged Chinese espionage in the US.
The Secretary of Energy, Mr Bill Richardson, has admitted that China obtained secret nuclear data during the Clinton administration as well as under previous presidents.
President Clinton said last March he was unaware of any Chinese espionage at nuclear laboratories during his administration. He was replying to queries about a classified report by the US Congress detailing leaks at the Los Alamos laboratory, which occurred in the 1980s but were discovered only in 1995.
A declassified version of this report is expected to be published later this month.
There are also reports that an American weapons scientist gave China secrets about radar technology to track submarines, according to the New York Times yesterday. The scientist, Peter Lee, has already pleaded guilty to handing over classified laser data to China in 1985.
Mr Richardson said: "There have been damaging security leaks."
Mr Richardson did not give details of the Chinese espionage but confirmed earlier reports that top-secret data about US nuclear weapons tests had been transferred by a Chinese-American scientist to his computer. Mr Richardson did not say whether the scientist, Mr Wen Ho Lee, who has been dismissed, passed on any sensitive information.
Mr Lee has denied handing over any information to China and claimed he assisted the FBI in counter-espionage efforts.
Last week, another Congressional report on the transfer of US satellite technology to China uncovered "very suspicious banking relationships", according to Senator Richard Shelby. He said millions of dollars were transferred to a small bank with ties to "a very suspicious character that is being investigated" in the ongoing inquiry into political fund-raising.