U.S. District Court Judge Gerald Rosen said Ashcroft's office "exhibited a distressing lack of care in issuing publicly prejudicial statements" about the case.

But the Detroit-based judge stopped short of ordering disciplinary action (news - web sites) or filing criminal contempt of court charges against Ashcroft.

Ashcroft made at least two statements at news conferences in which he praised the government's lead witness during the trial this spring.

The four defendants, all alleged Muslim extremists caught in roundups targeting hundreds of Arab and Muslim immigrants after the Sept. 11 attacks, were accused of belonging to a "sleeper operational combat cell" that prosecutors claim was conspiring to commit terrorist attacks in the United States, Jordan and Turkey.

One defendant was acquitted and a third was only found guilty of document fraud. Rosen, citing the withholding of evidence that may have helped the defense, said separately last week that he may order a new trial.

"Despite his unquestioned duty to represent the nation on matters of public concern, and his more specific responsibility to keep the nation informed of the Justice Department (news - web sites)'s efforts in the war on terror, the Attorney General has an equally vital and unyielding obligation, as the nation's chief prosecutor, to ensure that defendants are accorded the fair trial guaranteed them under the constitution," Rosen wrote in Tuesday's ruling.

"In this case, this essential balance was jeopardized, even after the court had issued specific warnings. Accordingly, the court finds that a public and formal judicial admonishment of the attorney general is the appropriate sanction to address this concern."

In his ruling, Rosen included a Nov. 26 letter to the court from Ashcroft in which he said he regretted making public statements about the case while it was still being tried. The top-ranking U.S. law enforcement officer added that his remarks at the time were "entirely inadvertent."