Police have admitted an officer dressed as a window washer to catch drivers committing traffic offences was inappropriate and say they will not repeat the tactic again.

Today FM reported one of their listeners sent in a video to Duncan Garner's show after spotting a police officer posing as a window washer to nab people using their phones behind the wheel in South Auckland.

After the man filming the undercover officer confronted him, uniformed police arrived on the scene and confirmed the window washer was a cop.

Counties Manukau Road Policing manager Inspector Tony Wakelin also confirmed in a statement to the Herald that a road policing operation was conducted recently at an intersection in Manurewa where an officer was dressed as a window washer.

But he said police acknowledge the officer in disguise was "not appropriate".

"We will be communicating with our staff this should not be happening in future.

"There were lessons here for their staff on the appropriate way to conduct these operations in future. And I will be ensuring those conversations will be had."

Wakelin said such operations, however, are an important part of police prevention and enforcement activities on New Zealand's roads.

"On this occasion, police were looking for motorists who run red lights or who were driving whilst using their mobile phones. Both of these offences are causes of death and serious injury on our roads," he said.

Wakelin said the purpose of the operation was to remind road users that using a mobile phone while driving, which included when stopped at traffic lights, was both illegal and dangerous.

"The use of a plainclothes officer to watch for these offences is a standard operating tactic to prevent death and serious injuries on our roads.

"Of which, there have been 20 deaths on our roads in Counties Manukau in 2022 to date.

"People who take the risk to run a red light are putting not only themselves but the lives of innocent members of our community at risk."

Wakelin said running red lights was a risk "not worth taking".