Pita Sharples wants communities to initiate a crackdown on gangs and is threatening to name and shame individual leaders and chapters and to investigate banning gang insignia if they don't respond.

The Maori Party co-leader also says he will identify schools that are failing to acknowledge and tackle gang-related problems.

Dr Sharples has worked with gangs for 30 years in various capacities, most recently through a community programme he initiated, designed to shed light on the impact of increased P and methamphetamine usage.

He says the gang problem is worsening and creating a culture of fear and intimidation in communities and schools, where youth gangs are emulating the "bullying tactics" of more established gangs like the Mongrel Mob. "I think that gang activities have reached a point that we can no longer afford to tolerate in this country. We cannot keep turning a blind eye."

Dr Sharples said the New Zealand Post decision to ban posties from delivering mail to three Hamilton streets after outbreaks of gang warfare was an example of how gang activities "impinge on our rights as free citizens". He had received numerous other anecdotes in recent weeks, which suggested to him how much more entrenched the problem was becoming. For example:

* At several large, reputable Auckland secondary schools, well known for achieving in sport and for high academic standards, some children are too scared to go to the toilet because others are in there with knives or ready to bully them.

* Students from one school in Auckland City are regularly fighting with pupils from a private boys school in West Auckland.

* Last week an 8-year-old walked into a fun parlour in Hamilton with a red shirt on, barking like a mongrel dog, and started trying to bully the other children off the machines.

* Government-funded community workers are doubling up on their visits to homes because they're frightened of the violence. Some have recently stopped after-hours visits for that reason.

Dr Sharples said despite genuine efforts by some gang leaders to tackle drug profiteering within their groups, they were failing because they lacked the authority to control behaviour.

And there was an inherent double standard, he said. "On the one hand you've got gangs trying to change their image and activities, on the other hand their rules allow ... members to be heavily involved at the worst level in the distribution and manufacture of P/methamphetamine."

Dr Sharples said several of the gangs were not Maori "but I recognise that a lot are Maori gangs and I would call on Maori tribes, tribal organisations, committees and Maori families to not accept the current behaviour.

"Either show us you're being responsible and helping us with this youth problem and stop the bullying culture yourself, or else know that we're going to try and get some legislation to ban your activities."

Asked what he might consider trying to have banned, Dr Sharples said, "Could we get away with banning gang insignia for a start?"

He refused to identify the problem gangs or the problem schools.

"But next time I will start naming. I'll start naming schools and the gangs and their branches so that each community will know it's that chapter right there at your doorstep."