Real-time facial recognition cameras will be rolled out in an Australia-first trial that will slash response times and boost community safety, police say.

The Overt Live Facial Recognition technology will be mounted on or near a marked WA Police van, and can scan crowds to instantly detect faces and compare them against targets who authorities are looking for or those banned from certain areas.

WATCH THE VIDEO ABOVE: Perth police trial live facial recognition cameras

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That includes more than 4000 people with outstanding warrants, the same amount on child sex offender lists who have served their sentence and are now in the community, serious offence suspects, and missing people.

“It’s the first time in Australia that we’ll be using this technology, but it is used in other jurisdictions, particularly in the UK,” WA Police Commissioner Col Blanch said.

Facial recognition has been used by WA Police for more than 14 years but under the current system it take hours to recognise wanted people, confirm it is them, and for authorities to move in.

By then, that person “has moved on”.

“(This trial is) about the speed in which we get those results and make arrests of people who are wanted by police or are in an area where they should not be,” the commissioner said.

Details of people on an “alert list” — a “strictly controlled” catalogue that consists “only of lawfully held police images” — will be uploaded into a database before the cameras get to work.

“The technology looks for the faces in the crowd, scans the crowd and where there is a certain threshold that has been predetermined that we think there is a match, the operator is then alerted that that person could in fact be the person on that list,” Blanch said.

“We still rely on a human to make that assessment. We don’t automatically arrest people because there is a match.

“We ask our experienced and trained police officers to make that assessment as to what actions they then take.” 

Blanch said the technology had a record of more than 2000 arrests in the UK, including “some examples where child sex offenders have been walking down the street, child in hand”.

Images of community members not on the alert list are automatically pixelated so not even the operator in the van can see them.

There will be no record-keeping of the captured data, authorities said.

Blanch said facial recognition is used by private companies extensively in WA “with no rules, with no storage requirements” and argued the police cameras were less intrusive and “about protecting people, not watching people”.

“The van has police written on the side. It has very clear signage about what it’s doing,” Blanch said.

“This is not about mass surveillance.

“The trial is to allow our community to see how it works, to understand how it works, to know what we’re doing with the data that is collected.”

Where you will see the cameras, and they will see you

Just a single van will be used during a trial that could stretch between three and six months, and it will be put to work in public places including Northbridge and at major events at Optus Stadium.

“Each location will be based on a risk assessment and who we are looking for,” Blanch said.

It is unclear how much money is being spent on the trial.

“The important part is to work with our community to look how it works, to have our community comfortable with using the technology, and then we can have that cost conversation after that,” Blanch said.

WA opposition leader Basil Zempilas said there is some form of risk with all technology but backed the cameras if the commissioner is satisfied all protocols are in place.

“I’ve always had the view, if you haven’t done anything wrong, you haven’t got anything to worry about,” Zempilas said.

“And I’m not sure that it’s any different when it applies to this.

“The police commissioner has said, we’ve investigated the technology, we trust the technology — I trust the police are going to use this technology in the appropriate manner.”