It states if the young person is consistently found unsupervised, CYF will be notified. That could see parents fighting for custody in the family court, Mr Nightingale said.
He said the letter also warned the parent or guardian could face a criminal charge of allowing their child to be without supervision, which carried a maximum fine of $2000. He said a young person didn't have to commit a crime for police to step in as the law allowed them to take action if they were concerned about their safety.
There would also be no more warnings for young people caught committing crime. The letter says the children will be arrested, fingerprinted and photographed and will need to be picked up from the police station. "We are finding children as young as 8 or 9 in the company of 12-year-olds. Some parents seem to be okay with that but that's not okay and that's exactly the kind of mindset we are challenging," Mr Nightingale said.
When police took children home, they found some parents or caregivers drunk with no idea where the children were, Mr Nightingale said.
"They have little grasp of their own situation let alone their children. Children are our future and our treasure. We need to look after them. But they are also committing adult crimes and putting themselves in situations where they are going to get hurt."
Sergeant Jim Harvey from the Rotorua police's Youth Services said on warm weekend nights it was not uncommon for police to take home 40 youngsters.
"We are now ceasing the taxi services. Mums and dads have got to put their hands up. They need to know where their kids are. We are about prevention. We don't want to be looking for bodies or missing kids."
CBK Craft Bar and Kitchen general manager John Knight said Eat Streat had started attracting groups of up to 30 youngsters walking from one end of the street to the other.
"They might be looking for opportunities. Someone might have left a bag and they grab it or something. It's just the fact they are gathering as a group, it can be intimidating to people."
Mr Knight said since police had started their operation he had already noticed a difference.