Students who sit in the aisles of overcrowded lecture halls during classes violate the state building code and create a fire hazard, the deputy chief of the Cambridge Fire Department said yesterday.

Francis J. Connelly, head of the fire protection unit of the Fire Department, said he was not aware of the problem until yesterday, but will take action to correct it as soon as possible. Connelly was unable to specify how he will enforce the regulations.

Humanities 9a, "Oral and Popular Literature," with an enrollment of 307 students, meets in the Geological Lecture Room, which has a capacity of 290.

"People sit on the floors and windowsills. If I don't get there early, I don't get a seat," Lisa M. Tolliver '80, said last night.

Amy E. Aldrich '78, said yesterday "it's hard to see the lecturer from the floor and I can't hear as well. There's a major inconvenience."

Natural Sciences 4a, "Natural Selection and Behavioral Biology," also holds lectures in overcrowded conditions. The enrollment for the course is 523, but Science Center B, where lectures are given, has a seating capacity of only 498.

"There are usually people sitting in the aisles. It's definitely overcrowded," Pat Reagan '79, said last night. "Today it was especially packed," he added.

The Cambridge Building Department is in the process of inspecting all Harvard buildings. Inspectors issue a certificate of occupancy for each lecture hall stating how many people may be in that room at any one time, the local inspector of Harvard buildings said yesterday. Any more than that number in the room constitutes a violation of the state building code.

If a member of the department witnesses a violation, he would "write a strong letter to whoever is in charge. If not corrected, there could be court action," the inspector said.

Robbie G. Mesheau, fire and safety inspector in Buildings and Grounds, said Science Center B is modern, with good lighting and exits, and overcrowding would not create a dangerous situation. But if a hall has more people in it than posted on the certificate of occupancy, "In my opinion, they are breaking the law," he said yesterday.

The Office of the Registrar is aware that these courses are too large. However, a spokesman said yesterday there is no other place to put them.

Alfred B. Lord '34, Porter Professor of Slavic and Comparative Literature, who teaches Humanities 9a, said yesterday his lectures are overcrowded, but he does not think it causes a problem.

"I've kept a watch on it. There are seats that are unused," he said yesterday. "Not all 300 students attend each lecture, unfortunately."

Robert L. Trivers '65, associate professor of Biology, said, "It's not really overcrowded. Usually people who sit in the aisles are latecomers who don't move to the front and take up empty seats."