A principal of Lindisfarne Anglican Grammar School, in Tweed Heads has used his school newsletter to lash out against global social networking sites, in particular Facebook.

The school's latest newspaper read in bold capital letters: "Get your kids off Facebook. This verbal sewer is harming your children."

Principal Chris Duncan's message meant to urge parents of their high school students to regularly monitor their kids, particularly their internet associations.

His newsletter usually issues an 800-word article tackling education or school issues, but was forced to alter the headlines after a 16-year-old student came to him asking for help after suffering verbal abuse on Facebook.

Duncan admitted he got exasperated with the situation, having known of other students who had suffered more.

"Some kids deal with it really well and other kids are mortally wounded by it and it's just the way different kids react to things," the Sydney Morning Herald quoted the principal as saying. He noted some children could be more vulnerable than others.

"I put it [the newsletter] out and thought this is going to offend half of the school community, but the feedback I've had is overwhelmingly positive," Duncan added.

The school administrator expelled last year two students for serious online harassment offenses against other students. On case was on Facebook, the other was on the school's internal email system.

He is not calling for a total ban on Facebook by the students and the school's community, but pressed parents to be more involved in their kids' lives. He said primary school age kids are too young to be on Facebook, while computer time should be limited on teenage kids.