A top Soviet Olympic official warned today that Western journalists could be expelled from the Soviet Union if the International Olympic Committee found their stories "offensive to the national dignity of the host country."

Vladimir Popov, vice president of the Moscow Olympic Organizing Committee, answering a question from a Soviet journalist at a press conference, declared that Olympic historians "know cases where journalists who have stepped beyond the limits of elementary decency and who have infringed on the basic norms of information in a civilized society have been deported from the games."

In what is interpreted here as a carefully planted warning, prompted by a question from the Soviet Novosti press service, Popov recalled that two correspondents had been expelled from Mexico during the 1968 games there for offending the host country.

Popov was asked to comment on an article in the London Daily Mail which speculated that security was lax at Saturday's Olympic opening ceremonies at Lenin Central Stadium and that a terrorist attack could have occurred as a result.

Popov said he had not seen the article, but the Moscow organizing committee might refer it -- and any other articles -- to the IOC for review and possible action if the Soviets feel their dignity has been infringed.

Then he added, "Why should we be in such a hurry? Let's wait and see. He said he would not like to see such an incident. Popov refused to discuss Western press coverage of an incident in Red Square two days ago, when four newsmen were grabbed and three hit by plainclothesmen as they were trying to cover a protest by an Italian gay rights activist.

"Too ugly to talk about, a disgusting case, a framed-up incident," Popov said of the attempted demonstration. The Italian, Vincenzo Francone, left the Soviet Union yesterday without further incident after being quickly taken into custody by the Soviets.

Popov then said, "The national dignity and feelings of our country have been offended. The individual who did this had to be dealt with . . . This has had nothing to do with the Olympic Games."

Sexual relations between men is a crime in the Soviet Union and Francone intended to protest that.

Security at the writers' press center was noticeably looser today, and many were passed through without having their briefcases and bags searched.

"We are accumulating experience," and Popov. "The security officers are getting additional expertise."