In a sharply worded ruling, United States District Judge Florence-Marie Cooper on Thursday blasted the US Attorney's office for ``conduct unbecoming a prosecutorial agency.''

Lawyers for Chinese-American businesswoman Katrina Leung had accused the government of illegally and unethically exacting a commitment from her former FBI handler that barred him talking to the defense.

The pledge was contained in an agreement that retired agent James Smith reached with the government this year allowing him to plead guilty to a reduced charge of failing to report his 20-year affair with Leung. Under long established rules, prosecutors are prohibited from obstructing a defendant's access to witnesses.

At a hearing before Cooper last month, Assistant US Attorney Michael Emmick disavowed any intent to prevent Smith from speaking to Leung's defense team. He blamed ``inartful'' language in Smith's plea agreement.

But Cooper cited a November 18 e-mail message to Emmick from Robert Wallace, senior trial counsel in the Justice Department's counterintelligence section in Washington, saying that the wording was aimed at ``preventing Smith from being interviewed by Leung's counsel because he is a repository of classified information.''

``In the face of that e-mail,'' Cooper wrote, ``anything short of an admission and apology on the part of the government is hard to imagine. Emmick did neither. Rather, he chose to ignore the e-mail.''

The plea agreement clause in dispute specified that Smith would engage in ``no further sharing of information relating to this case with Leung, counsel for Leung or the employees of counsel for Leung.''

Cooper said the evidence is abundantly clear that the clause was intentionally placed in the agreement to prevent Smith from talking to the defense.

And to make matters worse, she said, the prosecution subsequently engaged in a series of explanations and denials that ``compounds the problem by undermining the court's confidence in the integrity of the process.''

US Attorney Debra Yang issued a statement denying any prosecutorial misconduct.

Leung's lawyers, John Vandevelde and Janet Levine, said they were gratified with the dismissal. They described Leung as a loyal American.

Leung, a naturalized citizen, was recruited by Smith during the early 1980s to gather intelligence for the FBI during her frequent business trips to China, where she ingratiated herself with high-ranking government officials.

But starting about 1990, prosecutors said, she began working for the Chinese as well, feeding sensitive information about the FBI to her handler at the Ministry of State Security. Smith learned about her activities but covered them up and continued to vouch for her reliability, he admitted in his plea deal.

Leung was not charged with espionage but with illegally copying and possessing classified documents.