A major police operation in Whanganui, dubbed "Operation Swarm", resulted in multiple people being charged, cars being seized or impounded, with nearly 150 infringement notices issued.

Central District Police said in a statement they had "successfully disrupted" anti-social road users in Whanganui on Saturday night, targeting a "planned boy racer event".

Operation Swarm involved officers from across the district, including Taranaki, Ruapehu, Manawatū, Horowhenua and Tararua. They worked alongside bailiffs from the Ministry of Justice and vehicle inspectors from VTNZ, with Horizons Regional Council also providing support.

"We won't tolerate the anti-social behaviour on our roads and we will continue to target people who are intent on offending," Whanganui area prevention manager Inspector Neil Forlong said.

"Road policing is everyone's responsibility - that's why we brought staff in from different areas and from different work groups to conduct this operation, and why we're working with our partners to keep Whanganui's roads safe."

Six cars were seized by bailiffs for overdue fines and reparation, after they were stopped by police on driving matters. A further four cars were impounded under the Land Transport Act.

Five people were charged with driving with excess breath alcohol.

One person was charged with failing to stop for police and another with breach of bail.

Seven people were either forbidden to drive or suspended from driving due to behaviour on the night or excess demerits.

Fifteen unsafe vehicles were written off the road and one stolen car was recovered.

Almost 150 infringement notices were handed out and more than 500 people were breath tested.