There have been several cases of paedophiles "grooming" young people for abuse by chatting to them on the web, often by pretending to be teenagers themselves.

Tips for parents

Keep the computer near you Talk to your child about what they do online Keep a 'favourites' folder of agreed sites Ask your ISP about safety features

Mrs Hughes said: "Internet chatrooms have given young people in particular a virtual playground, an international school and a place to meet and make friends.

"Sadly the internet - like so many other technological advances - is not immune from criminal abuse and can bring its own dangers, not least to our children.

Parental guidance

"We all need to ensure that taking sensible precautions to protect ourselves and our children online should become as commonplace as it is to lock our doors or not talk to strangers in the offline world."

Mrs Hughes said the campaign would help parents help their children use the technology for fun while avoiding sexual threats.

A spokesman for the National Family and Parenting Institute said: "This campaign is something we are very glad about.

"It's a question of parents making sure they inform themselves of the dangers.

Children on the Net

4.8m under 16 online 1m under 14 online 81% have access at school 41% aged 15-16 use chatrooms 100,000 chatrooms available

"But they must also realise that these are far outweighed by the benefits of the internet, which is a terrific tool.

"One tip is for children and young teenagers to keep the computer in a public room.

"But for older children that can be difficult because they want privacy."

Ruth Dixon, deputy chairman of the Internet Watch Foundation, which supported the initiative, said that one case a month is going through the UK courts which involves a child being contacted through the internet.

Tips for young Net surfer

Never give address or phone numbers to strangers Do not meet a stranger alone Tell your parents if exposed to anything you dislike

But she added it was important to keep the issue in perspective and recognise that chatrooms can be innocent and used very positively by children meeting others from around the world.

Nigel Williams, chief executive of Childnet International, said "We believe very strongly in the benefits of the internet and launched a website called chatdanger.com devoted to teaching children about using it safely."

And Susie Renshaw, of Childline, which backed the campaign, added: "We've received calls from children worried about 'friendships' they've made on the internet or upset by things they've seen or read online."

A special booklet is available by phoning 0800 77 1234.

The booklet can also be downloaded from the Home Office's Wise Up To The Web internet site.