Leo F. Davenport, a 30-year veteran of the Cambridge Police Department, was sworn in yesterday as the city's chief of police, succeeding Nicholas Fratto who has been serving as temporary chief for the past six months.

James L. Sullivan, Cambridge city manager, appointed Davenport, who was one of two police captains who passed the civil service examinations. Fratto did not compete for the position of permanent police chief.

Last night at the Cambridge City Council meeting, Mayor Alfred E. Vellucci proposed that the city create the post of police commissioner, a civilian who would head the police department. The move would relegate the newly-appointed chief to the number tow position in the department.

Before the council could debate the proposal, Councilor Walter J. Sullivan exercised his charter right, and delayed consideration of the order until next week.

Vellucci made the police commissioner proposal in reaction to allegations that Central Square was becoming a haven for pimps and prostitutes.

Vellucci said yesterday that he favors the police commissioner proposal because the police chief does not have time to meet with civic and community groups and do an effective job in the police department.

"We want to improve relations between the police and the general public and devise methods so that the people of Cambridge can work cooperatively with police and so that the police can work cooperatively with the people of Cambridge," Vellucci said. He added that a civilian police commissioner would help to reach these goals more easily.

Councilor Thomas Danehy said the creation of a police commissioner so soon after the new police chief took office was "like a vote of no confidence."

Danehy added that some police officers loaf on the job. "I want 90 cents worth of work for every dollar we give them," he said.