A school is leading the fight against an alarming rise in pupils using the internet to bully classmates.

Blatchington Mill School in Hove is among the first in Sussex to sign up parents to combat intimidation in cyberspace.

Police have praised the school's initiative and are encouraging others to take a similar stand.

Three junior and two senior schools in Brighton and Hove have already adopted the scheme.

Police school liaison officers are planning to make presentations to parents of new students at secondary schools in the city in September.

Jim Browning, deputy head at Blatchington Mill, said most parents were not aware of what their children were doing when they used computers at home. Many create their own websites and use chatrooms with providers including MSN, Piczo and Myspace.

Some use the sites to bully and intimidate classmates and encourage friends at other schools to join in. Often threats are repeated in text messages sent to victims' mobile phones.

Mr Browning sent out a leaflet on internet safety to parents, asking them to sign and return it to show they were aware of the growing problem.

He said: "This term there has been a rapid rise in the number of incidents of cyber-bullying.

"Young people at Blatchington Mill have been writing extremely offensive comments about other students both here and at other local schools.

"The school's network filters out the use of websites and chatrooms where this can happen.

"We want parents to be aware this is happening at home. Students have computers in their bedrooms and parents usually have no idea what's going on."

He said one 12-year-old had used her web page to make offensive comments about other female students in her year.

He said: "The tone of the comments added to the forum by her friends is frightening. The foul and abusive language used was disgusting."

There is also a danger that paedophiles or other unsuitable people could be accessing websites set up by students.

Mr Browning said: "Some of the students use names which to them sound cute and innocent.

"But if you do an internet search using those names they often come up with results for pornographic and other unsuitable sites.

"The website of one Year 7 student revealed not only her age and date of birth but also her home and mobile phone numbers and email address.

"The potential misuse of this information by people cruising the internet is frightening."

He urged parents to monitor their child's use of chatrooms and personal web pages and said computers should be kept where they could easily be seen while in use.

Mr Browning said: "We had a good response from parents, many of whom had no idea this was going on.

"Staff at Blatchington Mill would be happy to advise other schools on what we are doing here to protect our students from misuse of the internet."

The Argus reported last week how a girl from Mid Sussex was prosecuted for cyber-bullying. The 16-year-old, who cannot be named for legal reasons, set up a website to ridicule a student who was the victim of a happy slapping attack.

The girl escaped a custodial sentence at Mid Sussex Youth Court but was given a referral order.

PC Andy Hart, schools liaison officer for Hove, said: "The staff at Blatchington Mill deserve every credit for their initiative.