A local judge yesterday urged a full investigation "to clean out Harvard Square" of drug peddlers.

"I have no use for those people in Harvard Square who are preying on students, especially the beatniks," Middlesex Superior Court Judge Frank W. Tomasello declared after sentencing a 19 year-old youth to a five-to-seven-year suspended sentence for selling drugs in the Square.

Tomasello's charges of large-scale drug traffic in the Square provoked an intense interrogation of Cambridge Police Chief Daniel J. Brennan by the City Council. Brennan said that the situation is not "dangerous" and defended his department's competence in handling any incidents.

"Any violation that comes to our attention gets immediate and constant attention," he declared. He said that most complaints received by the police proved to be "unfounded."

Councillor Walter J. Sullivan angrily disputed Brennan. Naming two Harvard Square restaurants, the Hayes-Bickford and the Waldorf, Sullivan said he had personally seen "needles and syringes" on the premises. "I would have to agree with Judge Tomasello. There certainly is a lot of drug traffic in and around Harvard Square," he said.

Heroin Traffic

Sullivan's report raised the possibility of heroin traffic in the Square. Most observers believe that the traffic is primarily limited to marijuana which is generally smoked by the user and is not addictive. Heroin is addictive and usually injected directly into the blood stream by the addict.

Sullivan and Councillor Alfred E. Vellucci exhorted the police chief to assign more men to the Harvard Square area. Vellucci had asked Brennan about a month ago--in an order passed by the council--to establish a special narcotics squad, but Brennan replied yesterday that "special members of the Crime Prevention Bureau" were adequate for the job.

Waldorf Policemen

Brennan also told the Council that the Waldorf restaurant had hired two Cambridge policemen to survey the restaurant two nights a week between midnight and 3 a.m. These officers he said, had not reported any drug traffic.

Dean Watson last night termed most estimates of drug traffic in the Square "greatly exaggerated." He blamed newspaper accounts of the alleged traffic for the distortions, and cited a recent article in the New York Times as "simply preposterous." The article reported that "Harvard students estimate that from one-fifth to one-half of the 12,500 persons studying at the University will have tried marijuana while in Cambridge."

Watson said, however, that he was "sure a few Harvard students have used [marijuana] and are using it." But he recalled "offhand" that "we've never caught any Harvard student pushing." He said anyone apprehended would "be dealt with very promptly."

Perennial Problem

Watson attributed most drug traffic in the Square to non-Harvard students. "It is a perennial problem a University town has. You always have a certain undesirable element hanging around trying to prey on the University community . . . There is not much we can do."

Watson's analysis seemed to blend, in part, with Councillor Sullivan's. After the Council meeting, Sullivan said that the peddlers "aren't students, but they dress like students." He explained that they were the same age as students and lived in areas around the University.

In the past month, four men, none connected with Harvard, have been convicted of peddling drugs in the Square area. All have been given five-to-seven-year suspended sentences.

Yesterday, Brennan criticized the judges' decisions. "Probations and suspended sentences won't act as a deterrent to drug peddlers," he said