Police are videotaping traffic passing through high-risk Auckland intersections to catch red-light runners and other offenders.

Inspector Andrew Coster, the police central city area commander, says Operation Focus is aimed at capturing evidence of drivers running lights or committing offences such as talking on cellphones or blocking intersections in rush-hour traffic.

"It's broader than just red lights," he said.

"It could be intersection blocking, which is a big frustration for drivers in the CBD - that causes major flow-on effects for traffic around the city."

Mr Coster said the videotaping was simply to assist officers on the spot. Their presence meant the police were entitled to add demerit points to infringement notices.

That is unlike offences caught on specialist road-side speed cameras, for which only fines can be imposed, because of potential difficulties identifying drivers.

Using videotape meant police patrols did not have to stop offending vehicles and risk causing extra congestion by interrupting traffic flows.

Officers were concentrating on high-risk intersections, where vehicle or pedestrian safety were particular concerns.

"The focus is very much on high-risk driver behaviour and to some extent offences that cause congestion."