New South Wales Premier Chris Minns has promised to "weed out" the "horrific behaviour" in the state's police force following "harrowing" revelations from an ABC News investigation.

ABC News has spoken to more than a dozen current and former officers who have made allegations of bullying, nepotism, sexism and a dangerous lack of support for officers suffering from PTSD.

They claim the toxic culture has led to a mass exodus from the police force, contributing to an almost 20 per cent shortfall in officers across the state.

Mr Minns today described the allegations as "very harrowing" and said current NSW Police Commissioner Karen Webb was committed to reforming the culture.

"I thought that the reports on the ABC last night were very harrowing, and as the premier, obviously, we've got major concerns about people who devoted their professional lives to the safety and security of others that have been bullied or harassed or even, even further than that, assaulted in the workplace," he said.

"One of [Commissioner Webb's] leading objectives as the police commissioner in NSW is to weed out that horrific behaviour and ensure that it's a safe place for new recruits or veterans to the NSW Police."

Mr Minns would not commit to an independent inquiry into the culture, but admitted the "job is not done".

"There's many oversights when it comes to NSW Police, many agencies, specific agencies that we uniquely fund, that have an oversight and investigation function for NSW Police," he said.

"Added to which you've got the police commissioner who's saying that this is a singular focus for her in terms of safety of her officers.

"The professionalism she's shown and their understanding of being a career police officer and also being a woman, I think, has been good for the force, but the job is not done."

Force failing on mental health issues, former staff say

As of early August this year, there were 2,279 vacancies in NSW Police.

A further 1,362 officers were on sick leave.

That's an almost 20 per cent shortfall of recruitment in NSW.

Many are fearful of speaking out against the organisation out of fear of reprisals and those still serving on the force are bound by a strict policy forbidding them from speaking publicly.

Those who have chosen to speak out, many under the condition of anonymity, say the toxic culture is driving hundreds of officers out of the force.

Former Senior Sergeant Mel Cooper, who left the force this year after a 30-year career, told the ABC the organisation was "still such a boys' club" and "nepotism is the highest I've ever seen it".

"The problem is if you speak up, the way you are treated afterwards by people that liked the person you've spoken about is appalling. You will be belittled and you will be badly spoken about," Ms Cooper said.

She said NSW Police had consistently failed officers suffering from mental health issues.

"Once you've been identified as having PTSD or an issue of some sort you become a liability," she said.

One officer said he sought help from his superiors for his declining mental health, but was told he had "a bad attitude" and ordered to continue working on patrols.

He tried to take his own life shortly after.

Another officer who still serving in the force but has been on sick leave since last year, says the culture left her contemplating suicide.

In response to detailed questions from the ABC, NSW Police said it would be inappropriate to comment on individual cases.

But it provided a statement from Acting Deputy Commissioner Dean Smith saying the force "does not tolerate bullying and harassment in the workplace".

He said the force "remains committed to providing all members with the highest levels of support so we can continue to attract, retain and provide the most effective policing service for the community".