The use of sponge bullets in the capture of a man on a violent rampage last year was a success, the police watchdog says.

Armed Offenders Squads around the country will now be equipped with the rounds - a bullet with a sponge tip which is fired from a gas launcher.

Photo: NZ POLICE

The investigation comes after the sponge bullets were used for the first time in the arrest of Aaron McDonald last year.

McDonald raped and murdered a 24-year-old woman and dumped her body in the boot of a car in a supermarket carpark in the Christchurch suburb of Woolston on 30 March.

He then attacked two tourists who were hitchhiking on the West Coast on 30 March, leaving the pair with stab wounds and broken bones.

The names of all three victims are suppressed.

Photo: NZ POLICE

After a 90-minute police chase and a five-hour armed stand-off, the police fired gas forcing McDonald out of his car, they then fired a sponge round at his legs which made him stumble.

A second sponge round was fired to distract him, while a police dog was released and police officers restrained him.

An Independent Police Conduct Authority (IPCA) investigation has endorsed the way in which police used the new tactical option during McDonald's arrest.

IPCA chairperson Sir David Carruthers said although McDonald did not sustain any serious injuries during the incident, the IPCA was asked by police to undertake an independent investigation given it was the first time the sponge round had been deployed by them.

"While the sponge rounds did not incapacitate Mr McDonald, they were effective in distracting him, and their use in conjunction with the Police Dog Team was effective."

The rounds will now be made available to Armed Offender Squads units around the country, who will receive appropriate training.

Superintendent Chris Scahill said the sponge bullets provided police with an effective tool that could help resolve dangerous incidents from a safe distance.

"The rounds can be used in instances where previously firearms may have been the only remaining option," he said.