Eighty opposition Republicans earlier wrote to Mr Clinton saying they wanted Mr Berger to resign.

"Mr Berger has failed in his responsibility as this nation's national security advisor by not properly informing you of the most serious espionage ever committed against the United States," the lawmakers said in the letter.

They said he knew of concerns about Chinese espionage, but delayed taking action.

Berger: 'We acted appropriately'

In his first public appearance since the publication of the damning congressional report, Mr Berger said he was not considering resigning.

"I believe that personally and within the White House, we acted appropriately when this information was brought to our attention," he said.

And on Thursday President Clinton said he had full confidence in his security adviser.

Mr Berger, who has been a strong advocate of expanding trade ties with China, is a long-standing ally of the president.

When questioned on the US television network, PBS, Mr Berger said he took proper action when he was told about two cases of security lapses at a weapons laboratory in 1996, although he did not tell the president until a year later.

When investigators returned in 1997 with more detailed information about broader and more systematic problems, Mr Berger said he then briefed Mr Clinton.

"We swiftly acted to implement the most sweeping reforms of counterintelligence in the labs in history," he said.