A street-art campaign aimed at attracting police recruits has been tagged within days of its appearance.

The NZ Police commissioned murals in Auckland, Wellington and Christchurch depicting real officers' experiences in the cities.

They were unveiled last week with the aim of attracting "smart young people" to the police force, said spokesman Grant Ogilvie.

But within days of the Auckland mural's unveiling, the two officers and the text in the artwork were defaced with orange paint spelling out the letters ACAB.

The scene, painted by Otis Frizzell, depicts two female officers, Constables Madeline Roberts and Julia Vahry, chasing an offender on foot.

The painting wraps around a building on the corner of Karangahape Rd and Day St in the central city.

Mr Ogilvie said the force expected the murals to be defaced at some stage.

"We're seeking to attract culturally aware and savvy young people as police recruits. Those responsible for defacing Mr Frizzell's artwork clearly don't fit this requirement."

He said the artwork would be cleaned up by a contractor today.

Frizzell said he felt "pragmatic" about the spraypaint attack.

"I thought it was inevitable, to tell the truth. It was inevitable because a lot of people who entertain themselves with street activities have a hair up their arse about the police.

"The campaign tried to appeal to a new, more edgy, educated, interested, more diverse crowd of people as recruits. People do respond to street art. So it felt like a way to get through."

Frizzell said he had no plans to repaint the mural.

"It's more like get it done, get it photographed and allow the reaction and people's views to carry it."

Artist Joff Rae said it was ironic that street artists who used to run from police were now working with them.

"Twenty or 30 years ago we knew the cops that were trying to arrest us. And they used to give us a smack on the hand."

The murals are part of a wider campaign by the advertising agency M&C Saatchi.

Online, social media and reality-TV ads will follow and outdoor media will be used.