As a Sept. 1 rollout date looms for a plan to equip 100 Boston police officers with body cameras, not a single officer has volunteered, prompting Boston’s police commissioner to warn he may have to force officers to wear them.

When a deal was announced with the city’s largest police union to use cameras in a pilot program, civil rights advocates praised the plan as a step toward greater accountability amid a national outcry over police killings of black men in other cities.

But with just a few weeks left before the program is supposed to begin, Police Commissioner William Evans acknowledged: “It’s been a hard sell.”

Police officials said last month that they had reached an agreement with the Boston Police Patrolmen’s Association to equip 100 volunteers — about 5 percent of the department’s force — with body cameras for the six-month program. Officers who agree to wear a camera will receive a $500 bonus if they complete the program.

Union President Patrick Rose and Vice President Michael Leary did not return several emails and phone messages seeking comment on the lack of volunteers.

Police in Boston and other cities have expressed concerns that cameras could inhibit interaction with people in crime-infested neighborhoods, particularly informants or witnesses who may be reluctant to talk to police if they worry the video could be seen by criminals who could retaliate against them.

They also say the costs of the cameras and video storage could divert money from other resources, including weapons and protective gear. Police union leaders in other states have also said they fear cameras will be used by police administrators to discipline officers for minor infractions.

Evans initially said he doesn’t think body cameras are necessary in Boston, where, he said, officers have built strong relationships through community policing.

“I think we’ve shown what kind of a class act department we are, but we are going to give them a try and see if the results are positive,” Evans said in an interview with Boston Herald Radio in April.

Activists in Boston have called for police body cameras for two years, since the shooting of Michael Brown, an 18-year-old black man, in Ferguson, Missouri, by a white police officer. A string of other police shootings since then have sparked protests around the country.

Matthew Segal, legal director of the American Civil Liberties Union of Massachusetts, said he hopes Boston officers will volunteer to wear the cameras.

“I hope it doesn’t come to a police department being forced to wear body cameras against its will,” Segal said. “Ideally, body cameras should be a tool for building trust between civilians and police officers. What we’re worried about now in Boston is that doesn’t seem to be happening.”

Boston City Councilor Tito Jackson, a supporter of police body cameras, praised Boston police for quickly showing community leaders surveillance video of police-involved shootings, including the June 2015 killing of a man who allegedly waved a military knife at police and the March 2015 shooting of a suspect after he shot an officer in the face.

“Those relationships take a long time to build and a very short time to lose,” Jackson said. “This is a component to ensuring that we are able to sustain those relationships.”

The volunteer aspect of the pilot program has drawn criticism from advocates who say only officers with good records are likely to sign up.

“Really what we wanted to see was, would the presence of the camera change the behavior of a problem officer? Will that change how they talk to people? Will that change how the civilians they’re interacting with interact with them?” said Segun Idowu, co-organizer of the Boston Police Camera Action Team.

Boston police spokesman Lt. Michael McCarthy said the goal of the pilot program is to determine whether cameras can be a useful tool and should be assigned to officers throughout the department.

“We have officers who may be hesitant to be the first to volunteer for such a high-profile program,” McCarthy said. “It is a pilot program — nothing’s permanent yet — and we would hope that officers would be encouraged to come and volunteer.”

Police in some other states have also shown reluctance to wear body cameras. In Connecticut, only 12 of the more than 100 law enforcement agencies in the state have shown interest in a new state program that encourages them to begin using body cameras. Some Connecticut state troopers are already using cameras, as well as police in Newtown, Hamden, Watertown and several other towns.

(AP)