Cops sifting video to catch riot ringleaders

The technology thought to have been used to instigate Gisborne's New Year's Eve riot is now being turned against the ringleaders.

Police are trawling through cellphone footage as they consider more serious charges against the culprits behind the mayhem that marred the BW Summer Festival.

Police appealed for help from those who filmed the ruckus, which ended with 63 arrests and dozens being treated for injuries after rioters overturned vehicles, torched tents and hurled full cans of alcohol.

Most of those arrested have been summonsed to appear in court facing charges including disorderly behaviour, assault and assault with a weapon.

But those identified as ringleaders could face charges of inciting a riot, which carries a maximum sentence of two years' imprisonment.

"Our investigations into the incident are continuing and it doesn't stop when people have been arrested," Senior Sergeant Steve Sutherland said.

"We want to see as much footage as possible so we can identify those who took an active part in the riot."

Police have also been viewing videos posted on media and social media sites.

Footage on YouTube showed projectiles flying through the air, fires smoking, and young people clutching alcohol and jumping between a flattened divide that had separated the crowded campsites.

"It would be very helpful for our investigation to gather as much information ... and we hope those who hold that information will be able to assist us," Mr Sutherland said.

Police had also found evidence that suggested the violence had been preplanned on social media.

Tairawhiti area commander Inspector Sam Aberahama told Radio New Zealand that certain comments on social media indicated "there was going to be a breach of the fence between two camps". He said the troublemakers "had a plan and they were going to carry it out".

On Thursday, Gisborne District Council condemned the rioters and said it was "appalled" that a small group of mischief-makers was able to spoil what had been a well behaved and successful event.

In the face of huge pressure from festival-goers, event organisers had withdrawn their application for an on-site liquor licence that would have banned BYO alcohol.

But the council stated it was clear "those who were determined to make trouble would have done so no matter what the licensing arrangements".

"We will certainly be looking to ensure that the organisers that lease the land from us take every possible action to avoid this happening again," council chief executive Judy Campbell said.

Riot videos can be emailed to intel.eastern@police.govt.nz.