In what prosecutors said was a rare seizure of an adult film at a theater in Northern Virginia, Fairfax City Police confiscated the X-rated "Love in Strange Places" this week from the Carousel Theatres on Lee Highway in Fairfax City.

A telephone tape recording at the theater told callers yesterday: "Thank you for calling the Carousel Theatre. In the Carousel One, "Love in Strange Places" will not be shown due to a mechanical problem."

"It sure is a mechanical problem," said Fairfax Deputy Commonwealth's Attorney Steven A. Merril. "We've got their film."

The film was seized Tuesday night after Fairfax City police Detective Douglas C. Cromarty and Special Magistrate Kenneth A. Borchadt viewed the movie in the Carousel One Theatre and found it to be in violation of Virginia's obscenity statue.

In an affidavit filed in support of a search warrant, police said the movie "depicted sexual conduct showing sexual reiations including penetration, ejaculation and oral sodomy, lacking literary, artistic, political or scientific value"

The owner of the Carousel Theatres, John Allsbrook of Reston, said yesterday he was "very surprised" when police seized the movie.

"I don't know why they did it," said Allsbrook, who noted that he started showing X-rated movies about a month ago to "drum up a little business." He said Fairfax City police planned to meet with him last night to explain the seizure.

The last seizure of and X-rated film in Northern Virginia occured at a Fairfax County drive-in, after complaints were recived that motorists driving past the outdoor theater could see explicit sexual activity on the screen, Merril said.

The prosecutor said most complaints about movies considered objectionable in the Northern Virginia suburbs are handled informally by police, who ask the theater manager to stop showing a film that has elicited complaints.

One theater operator, Leonard E. Poryles, coowner of the Shirley Duke Three Theatres on Rte. 236 in Alexandria and the Biograph Theatre in the District of Columbia, reacted angrily yesterday to news of the Fairfax City action.

"I thought this was a dead issue these days," saidPoryles whose theater in Alexandria regularly shows X-rated films. "most people in this day and age believe adults have a right to see what they want. I would think the prosecutors in Fairfax would have better things to do than cover the eyes of 100 moviegoers."

Prosecutors and Fairfax City police supervisors said yesterday they could not explain why no attempt was made to persuade the owner of the Carousel Theatres to stop showing the film before the seizure was made.

"I don't know why the decision was made to do it this way," said Fairfax City Deputy Chief Robert D. Russell.

Assistant Commonwealth's Attorney Ray Brownell, who is handling the obscenity case, said yesterday that no decision has been made yet on whether to prosecute theater owner Allsbrook an a charge of displaying obscene materials, a misdemeanor punishable by up to one year in jail or a $1,000 fine.

"If this were just a lark and we can persuade him not to do it again, then we may not prosecute," Brownell said.

Three suburban theater managers interviewed yesterday said the generally accepted policy for X-rated movies is to show the so-called "cool" version of the films, which omit depictions of sexually-aroused organs and actual intercourse.

"It is our policy to show the 'cool' versions in the suburbs," said Roy Thompkins, division manager for Neighborhood Theatres Inc. in Falls Church.

"Love in Strange Places," according to police, was a "hot" X-rated film.

Movie house owner Poryles, whose theater in Alexandria has been showing the soft-core film "Misty Beethoven" continuously for nearly three years, said the suburbs have "an incredibly large demand for X-rated films.

"The X-rated films do particularly well in the suburbs on Saturday, when couples go out," Paryles said.