Police are using their extra tools to tackle gangs

A Gang Arrest Warrant has been put in place for much of the lower North Island.

Police say both the Nomads and the Mongrel Mob have been involved in dangerous activity.

Four gang members have been arrested and officers have carried out a series of search warrants in Hawke's Bay.

Canterbury University Emeritus Professor Greg Newbold says those warrants are an effective tool.

He says they mean officers can put extra pressure to disrupt gang activities.