Commenting on a story in the New York Times that China stole US nuclear secrets and used them to improve its own arsenal, the officials, denied one aspect of the report -- that Clinton tried to downplay the espionage because it clashed with efforts to improve ties with Beijing.

``Once he learned of it he increased security at the labs. It was something that happened long time before,'' the official said. At the same time China, fresh after talks with US Secretary of State Madeline Albright last week, downright refused to accept that it ever indulged in the reported act.