The bribery trial of Alexandria Commonwealth's Attorney William L. Cowhig opened yesterday with both defense lawyers and the judge voicing fears of prejudicial publicity.

Speaking to reporters in the courtroom, Prince William County Circuit Court Judge Percy Thornton Jr. described himself as "neither a freak nor a weirdo in from the country" selling "eggs and goat's milk" and lectured the press to "report the facts impartially and without bias or slant... Sensationalism has no place in court."

Chief defense lawyer Louis Koutoulakos picked up the judge's theme repeatedly, telling Thornton and some prospective jurors that "massive publicity" had "pilloried Cowhig" before he had been brought to trial.

Koutoulakos likened the case to the sensational 1954 Ohio murder trial of Sam Sheppard, whose conviction was overturned because of prejudicial publicity.

Thornton, saying he already had had "one encounter with a television cameraman," issued "housekeeping rules" restricting press interviews to outside Alexandria's Circuit Court building.

Yesterday's day-long session was spent selecting seven men and seven women as jurors, two of whom will be designated alternates.

All 14 said they knew of Cowhig and his Aug. 3 indictment on a charge that he asked for and received a total of $32,000 in bribes from an Alexandria bingo game operator while serving as the city's chief prosecutor. But each juror said he felt he could still render an impartial verdict.

Several said, in response to questions, that they had played bingo in the past.

Shortly after Thornton's opening remarks, Cowhig, 53, made his first public statement about the indictment, telling the judge in a loud voice, "I am not guilty, your honor."

Cowhig is accused of seeking the bribes in exchange for shielding Dirgham Salahi, director of the Montessori School of Alexandria Inc., whose school's bingo games grossed more than $500,000 last year.

The games allegedly violated Virginia's law governing bingo. Salahi, who has been given immunity from prosecution, is expected to be the key prosecution witness against Cowhig.

Special prosecutor Edward J. White, answering defense complaints about publicity, said yesterday that he felt a stern warning by Thornton to the jurors would be a sufficient alternative to sequestering the jury. Thornton told the jurors after they had been chosen that they would be sequestered if that proved necessary.

Defense lawyers have not asked for a change of location of the trial, or for a dismissal of the charges based on publicity.

Thornton yesterday denied a defense motion for dismissal based on a parallel federal investigation of Cowhig. But the judge ordered White to turn over a police document showing in part that in 1976, Salahi received a $50,000 cash loan from an Egyptian citizen.

Thornton was assigned by the Virginia Supreme Court to preside over the trial after Alexandria's three Circuit Court judges disqualified themselves. Cowhig has served as commonwealth's attorney in Alexandria since 1973.