As the Police Department prepares to mount more than 500 surveillance cameras across the five boroughs, a group of City Council members has proposed legislation to bolster security at city bars and clubs.

The bills are being introduced following two incidents in recent months in which young women were murdered after being last seen outside Manhattan bars. One proposal would require legal certification of bar employees who handle security. The second would require bars and clubs of a certain size to hire a police detail to patrol the street outside, a move the NYPD has opposed.

“We need to make sure that the nightlife of the city of New York is a safe nightlife at the same time as it is a vibrant and exciting nightlife,” the sponsor of one of the bills, Council Member Alan Gerson of Manhattan, said as he stood outside the Falls, the SoHo bar where a 24-year-old graduate student, Imette St. Guillen, was abducted and later murdered in February. The bar’s bouncer, Darryl Littlejohn, has been charged in her death. In January, Nicole duFresne, 28, was shot and killed during a botched robbery as she stood outside a Lower East Side bar.

A state law already requires that security companies register and fingerprint their security guards, but Mr. Gerson said his proposal would be broader and apply to any employee that performs security functions, including those that take tickets at clubs or check IDs at bar.

Mr. Gerson and a council member of Brooklyn, David Yassky, also renewed a call for bars and clubs to be able to hire police officers to patrol outside, a proposal that bar owners have long favored but which the police department has resisted. A police spokesman, Paul Browne, would not comment on the specific proposal, but said the department had opposed the idea in the past “because of traditional restrictions in police officers having even a perceived vested interest in a licensed establishment.”

The proposals came as the council’s Public Safety Committee convened a hearing to examine the police department’s plans to significantly expand its use of video surveillance by installing more than 500 cameras primarily in high-crime areas throughout the city. While the city’s public housing developments and subway stations have surveillance cameras, the police currently operate only about two dozen, officials said.

The cameras will be installed in two phases, beginning in Brooklyn at 253 locations. They will be clearly marked as police cameras, the head of the department’s technical assistance response unit, Deputy Inspector Delayne Hurley, told the committee.

The police also are in the early stages of planning a much larger anti-terrorism initiative for Lower Manhattan, modeled on London’s “ring of steel” program, which is likely to include hundreds or even thousands of cameras.

Plans for expanded use of video surveillance have raised concerns over privacy among civil liberties advocates, who say the cameras could be prone to abuse.

The executive director of the New York Civil Liberties Union, Donna Lieberman, sought assurances that guidelines would be in place for the use of the recordings generated by the cameras, as well as for how long the recordings would be kept before being destroyed. She also questioned the effectiveness of surveillance cameras in combating crime. When Mr. Vallone said police used cameras to identify suspects in the recent death of a New York University student in Harlem, Ms. Lieberman countered: “Let’s not forget that video surveillance did not stop that terrible crime.” Cameras, she said, “can’t come to the aid of someone in trouble. They can’t step in and stop crime.”

Mr. Hurley said department supervisors would be assigned to units monitoring the cameras. Mr. Vallone said he would press the department for more specifics on their guidelines for the program, but he was not persuaded by Ms. Lieberman’s testimony. “I believe the benefits of cameras outweigh the potential for harm,” he told her.