The United States intelligence official who first raised fears of Chinese nuclear espionage at the Los Alamos laboratory has resigned.

The official, Notra Trulock, said he had left his post as the Energy Department's deputy director of intelligence because the government had failed to support him.

Notra Trulock says the government investigation failed to support him

Mr Trulock's resignation comes amid further controversy over his allegation that the Chinese American nuclear scientist, Wen Ho Lee, passed on classified information to China.

Mr Lee was sacked from his post but has not been charged with any crime and has always denied the allegation, as has the Chinese Government.

Government report

Mr Trulock told the Washington Post newspaper that he was resigning because a government report released last week had failed to back him.

Wen Ho Lee denies the charges

He described the report as a whitewash, and said it should have held senior Clinton administration officials responsible for security lapses at Los Alamos.

His resignation is the latest blow to the credibility of US allegations that China stole classified information, which enabled it to develop minature nuclear warheads.

Accusation of race bias

Mr Trulock himself has been under mounting criticism over his methods. Senior intelligence officials have accused him of ignoring other employees at Los Alamos who had similar access to nuclear secrets, and focussing on Wen Ho Lee because of his Chinese-American background.

Mr Trulock has denied that race played any part in his investigations.

But there is also wider disagreement over how much classified data China obtained, and where the information came from.

Some US officials argue that it was available from public sources, or through what they describe as China's indigenous espionage efforts.