People as young as 10 are being included on a secretive blacklist kept by New South Wales Police, which experts say is criminalising children.

Lawyers from the Public Interest Advocacy Centre (PIAC) and the University of New South Wales (UNSW) have released a study into a police policy known as the "Suspect Target Management Plan" (STMP).

The details of the program are closely guarded by NSW Police, but authors of the report believe thousands of people may be targeted as part of it.

One of the authors, PIAC senior solicitor Camilla Pandolfini, said the first time people realise they are in the program is when they are routinely harassed by police.

"Individuals aren't given a formal notification that they're placed on the STMP, but what they do experience is repeated stops and searches every time they're out on the street," she said.

"And then police showing up at their homes at all hours of the night, all hours of the morning, sometimes a couple of times a day, sometimes a couple of times a week."

Dr Vicki Sentas from the University of New South Wales has spent years researching the STMP after stumbling across it while working at Sydney's Redfern Legal Centre.

"[We had] young people coming in saying, 'I'm on a STOMP', and we were saying 'What is this STOMP?'"

Dr Sentas describes it as a troubling shift away from traditional policing.

"Traditional policing is about investigating an offence that's actually happened in order to find the offender.

"What the STMP does, it is not based on police suspecting that someone has done something, or they're about to do something.

"Police target people on the STMP because of who they are."

'It's like a secret blacklist'

Police have refused to reveal the methodology of the program to researchers, according to Ms Pandolfini.

"It is a little bit like a blacklist, it's like a secret blacklist," she said.

The report recommends that children should not be involved in the STMP program. ( Flickr: Curtis Cronn )

Researchers were able to obtain sample data from 10 Local Area Commands which revealed that both young people and Aboriginal and Torres Strait Islander people are over-represented.

"For example, in one local area command, at one particular point in time, all 10 people subject to an STMP were Aboriginal," Ms Pandolfini said.

"In another local area command, a young person who was only 10 years old was subject to an STMP."

The criteria for being included or removed from the STMP is secret, but Ms Pandolfini said some of the people targeted have no criminal history.

"There is a whole range of offences that young people might have committed and in fact, some people might not have even committed offences at all," she said.

Police were 'aggressive': grandmother

"Anna", as she wants to be known, said her grandson was one of those on the list.

In late 2013, police in the New South Wales town of Walgett started checking on the then 19-year-old multiple times a day.

Anna described how the police would show up at the house at 9pm and 10pm, and also on Sunday mornings.

"They'd be quite aggressive at the door — you know, swearing and things like that," she said.

Her grandson had what she calls a minor, non-violent criminal history in the Northern Territory, for which he was serving a community service order.

But Anna said he was holding down a job and getting his life back on track when police began showing up on a daily basis and routinely searching him in the street — a pattern that continued for nine months.

"[It was] to the point where he said, 'I don't even feel like I can go out of my own house, and even in my own house I'm not feeling safe'," she said.

Anna said there was never any paperwork or formal notification as to why her grandson was targeted, and as far as she knows he may still be on the STMP.

The report, published by the Youth Justice Coalition, recommends extensive changes to the program's transparency and approach to children.

"Our research recommends that the STMP not be used now in relation to children under the age of 18," Dr Sentas said.

"The most urgent thing is that the STMP policy and the guidelines and, importantly, the risk categories which are purportedly used to put people on the STMP, need to be publicly available."

A statement from New South Wales Police describes the program as a "crime prevention strategy" which is overseen by a senior police officer in every case.

It said STMP nominees are treated with "respect and tolerance" and that a risk management framework is used to make sure the right people are being targeted.