Anybody who looks at this case and doesn't know the circumstances of it is going to say, 'Why?' And I think that's what the president kind of naturally asked

Attorney-General Janet Reno

Mr Lee was released after pleading guilty to a minor charge of mishandling classified information.

Racial claims

An apologetic judge said at the time that the government's actions had "embarrassed our entire nation".

Mr Lee was initially portrayed as a spy for China, although these allegations were unproven and no formal espionage charges were ever filed.

As part of the plea bargain agreement, Mr Lee was sentenced to 278 days, one day less than he had already served.

The three-year-old case was marked by claims that the scientist was unfairly singled out for investigation because of his race.

Mr Lee's family has always maintained his innocence

After meeting Mr Clinton on Friday to discuss the case, Ms Reno said she had ordered the Office of Professional Responsibility - which investigates misconduct by Justice Department prosecutors - and Federal Bureau of Information agents to carry out a review.

Mr Lee had been charged with 59 counts of breaching national security at the Los Alamos nuclear weapons factory, and faced life in prison if convicted.

Co-operation

In exchange for his guilty plea 10 days ago, the government dropped 58 counts against him.

The federal judge in the case said he was also sorry that the plea deal prevented disclosure of information that would have shed light on the reasons for Mr Lee's detention.

Mr Lee lost his job at the laboratory against a background of widespread allegations that he had compromised what were described as "the crown jewels" of US nuclear weapons technology.

Ms Reno on Friday defended the decision to keep Mr Lee in solitary confinement because much of the case hinged on the whereabouts of seven computer tapes onto which the scientist had admitted downloading sensitive information.

As part of the proposed deal, Mr Lee agreed to co-operate with investigators as they try to confirm his account that he destroyed the missing tapes.

Asian-American leaders have demanded the White House appoint a special commission to investigate whether racism played a role in the treatment of the scientist.