Papua New Guinea's police force has revealed it has dismissed 87 officers for misconduct in the past two years, half of them for police brutality.

Some of the worst cases have involved the rape of prisoners in custody while the offending police officers were on duty.

Superintendent Dominique Kakas has told Radio Australia's the PNG police force has a "zero tolerance" approach to police brutality.

He says some officers have been given lengthy jail sentences for such behaviour.

"Whenever that is reported, we take a tough stand on that," he said.

"We've been encouraging members of the public that if they've been victims of police brutality, to come forward and report the matter."

Superintendent Kakas says in most cases offending police are given the maximum penalty, which is dismissal of the officer concerned, and will be tried in a criminal court if appropriate.