Kiwi parents should be worried by a study naming Australia as the world's worst place for cyber-bullying on social networking sites, say experts.
A survey of 24 countries by Ipsos Social Research Institute found almost 9 in 10 Australian parents said their child or another they knew in their community had experienced harassment on sites like Facebook.
The figure was much higher than the global average of six in 10.
In New Zealand, parents had similar cause for concern because the level of cyber-bullying was similar here - and on the increase, said Netsafe executive director Martin Cocker.
"It certainly has (increased), just basically with the proliferation of technology. We are working with our counterparts in Australia and we seem to be dealing with the same thing in similar quantities.''
The rise in cyber-bullying was particularly prevalent on popular sites such as Facebook, which bullies used for intimidation, and harassment, said Mr Cocker.
There has also been an increase in the number of fake profiles designed to damage a person's reputation, he said.
One in five students reported being bullied in any 12-month period, according to a Netsafe survey.
The figures were similar for cyber-bullying, with one in four or five young people believed to be affected, said Mr Cocker.
The Ipsos study involved 18,000 students from countries including the USA, UK, Russia, Germany, Australia, China, Turkey, Poland, Mexico, Brazil, India, Indonesia and Saudi Arabia.
It revealed Australian children were the fifth most likely to be the victims of cyber-bullying overall behind India, Indonesia, Sweden and Canada.
Other platforms covered by the study included mobile phones, online chatrooms, email and online instant messaging.
Kidsline and Lifeline spokesman Dylan Norton said bullying could have a big impat on young people in New Zealand.
"It can have a really big effect on behaviour at school, mood and things like depression, which can lead to suicidal behaviour. It can really have a significant effect, he said.
In 2009, Rotorua teenager Hayley-Ann Fenton took her own life after being cyber-bullied. The 15-year-old died in hospital hours after receiving threatening text messages from the wife of her ex-boyfriend.
Elina Tiumalu was later convicted on charges of intimidation and Hayley-Ann's mother Lesley last month backed changes proposed by the Law Commission to protect victims of cyber-bullying.
The commission recommends giving victims the chance to hit back at their tormentors through a new, easily accessible internet enforcer capable of imposing fines, ordering apologies or terminating the offender's internet account.
It also proposes new laws to tackle online harassment, which would make it a criminal offence to encourage someone to commit suicide, to post "intimate images'' online without the subject's consent and to "maliciously impersonate'' someone on social media such as Facebook and Twitter.
Kidsline and Lifeline offer free counselling to hundreds of people each year seeking support for issues, including cyber-bullying.
Mr Norton urged parents to be aware of warning signs their child is being bullied, which can include withdrawal from doing things they enjoy and major changes in behaviour.
Parents should monitor their children's internet use, get involved in their online lives and speak to them about appropriate behaviour on the internet, said Mr Cocker.