New South Wales Police Minister Stuart Ayres says mini video cameras on the vests of frontline police officers will provide greater transparency about incidents involving the public.

The NSW Government is rolling out $4 million worth of body cameras, which will be worn on officers' vests whenever they are on the job.

Mr Ayres says video footage of incidents may be used in court.

He says the presence of cameras could make people rethink their actions when they interact with police.

"The video devices make a significant contribution to fighting crime, it also allows police officers to record actions that they've been involved in," he said.

"We found that video on police makes a big difference to the behaviour of people interacting with police so it's a very positive step forward."

Mr Ayres says the cameras will also help with police training.

"The more we have the body-worn video, it'll allow us to evaluate critical incidents as well, so police officers will know there'll be a record of that," he said.

"It's important for their own training and own feedback, but it's also important to know that people who are interacting with police have the potential to be videoed as well."

NSW police say the cameras are being tested in other parts of Australia including regional NSW and Melbourne.