A row has erupted in French schools over moves to suspend, expel and even prosecute pupils who insult teachers and classmates on their internet blogs.

No French children have been brought to trial yet, but four are facing legal action for either defamation or for infringing the right to privacy by publishing unauthorised photographs on the web. Dozens have been disciplined by their colleges and lycees.

Parents have expressed anger at the clampdown by head teachers, which follows the rapid spread of personal web logs - known by the English language abbreviation, blog.

But staff in French secondary schools say action is necessary to stop an insidious attack. With an estimated 3 million French children possessing their own online diary, and 6,000 new ones created every day, adolescent chatter is being posted on the internet.

The language, with its text-message type grammar, is barely comprehensible to adults. The themes, however, are familiar: teenage heartache, discussion of pop idols, bad jokes, swear words and insults.

At least eight pupils have been expelled this year after staff discovered what had been written about them. In Chamalieres in the Auvergne region of central France, an adolescent was thrown out of his secondary school for describing his teachers as "old farts" and "imbeciles". Three other children were suspended for three days each for adding comments in the same vein.

"My son excused himself personally to all the teachers he mentioned in the blog," said the mother of the boy who was expelled. "This punishment is excessive."

She is being supported an association of other parents at the Teilhard-de-Chardin school. One, Fanny Duhot, said: "We are really upset at the injustice of this measure. He is a brilliant pupil but it is going to follow him throughout his life at school. It is one of the worst punishments that anyone can receive."

Once such messages were scribbled in school books or spoken in the playground, but now that they are available for public consumption on the web, teachers say many fall foul of French libel laws, which carry a maximum penalty of one year in jail and a €45,000 fine.

Another teenager was expelled for displaying photographs of teaching staff - along with his own comments on them - taken on his mobile phone during a school trip to Versailles, outside Paris.

"It was like a personal diary, and I only gave the address to friends," the 14-year-old boy told the newspaper, Liberation.

"I didn't realise a teacher would stumble on it. I was just having a laugh with my mates. I said I'd heard a teacher fart in the toilets, and that another was a happy idiot and that she liked being touched up."

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