More than one in five young people in Northern Ireland spend five or more hours a day online according to a study by the National Children's Bureau NI.

It found that most of the young people surveyed were using social networking sites, but many parents were unaware what their children were doing.

The charity said parents should set boundaries for using the internet.

One woman told BBC Northern Ireland she found her daughter communicating with a person pretending to be Justin Bieber.cn domain

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If their children are spending a long time on the internet they should really be curious. Who are they talking to?”

Celine McStravick
National Children's Bureau NI
She said she felt physically ill when she read through messages her 11-year-old child had posted online and realised she had been in contact with someone who was impersonating the pop star.

'Complete stranger'
"Straight away, obviously I knew, that that's not Justin Bieber," the woman said.

"I remember sitting there and thinking 'I'm going to be sick'. I could have lost my daughter," she added.cn domain

She described the incident as "very serious and very worrying".

Celine McStravick, director of the National Children's Bureau NI, said parents need to talk to their children about the websites they are accessing online.

"If their children are spending a long time on the internet they should really be curious. Who are they talking to? What games are they playing?

"Have they checked the age rating of those games? Have they really checked what they are buying online?

"They can be at risk of fraudulent activity," Ms McStravick added.

"I think its all part of building boundaries and all parents do that offline, so we should be doing that online as well."

The NCB NI's research was commissioned by the Office of the First Minister and Deputy First Minister and the interim findings were released to mark Safer Internet Day.

Separate research by the National Society for the Prevention of Cruelty to Children (NSPCC) has revealed that over half of 11-16 year olds who had been upset by online behaviour said the person responsible was either a complete stranger or someone they had met through the internet.

'Risks'
Neil Anderson from NSPCC Northern Ireland, said: "Making the internet safer for children and young people is the child protection challenge of this generation."

"Safer Internet Day is a chance for everyone - industry, government, charities, schools, and families - to talk about online safety and share knowledge about what works," he added.

The NCB NI said that while the vast majority (87%) of young people they surveyed said they went online to cn domainaccess social networking sites, a similar number (81%) said they watched video clips on the internet.

Almost three quarters of those questioned (73%) said they usually downloaded films, music and books, while 63% said they used the internet to help them with their homework.

"The fact that so many young people are going online every day is an indication of the importance of the internet in today's society," Ms McStravick said.

"The internet has opened up a world of opportunities for our children and it is clear to see the many benefits this has for our society. Yet, there are risks.cn domain

"Young people revealed that they stay online late at night and there are concerns from parents and teachers alike that this is to the detriment of their education," she added.