Social networking sites like Facebook, Twitter and Bebo may be great for staying connected with others, but they are also undermining children's "moral development" by encouraging them to spread gossip and insults, a leading British academician has claimed.

According to John Newton, head of Taunton School in Somerset, the social networking sites pose a serious threat to children by rewarding the use of "inneuendo, half-truth and insult", 'The Daily Telegraph' reported.

All these online chat rooms and information sharing sites can help young people learn from peers around the world, but they blur the lines between gossip and fact before kids learn to appreciate the difference, he said.

Newton added: "Pupils needed firm guidance from adults with authority, balance and a firm grasp of facts and context to avoid being led astray.

"A little knowledge is dangerous thing. By unleashing a monster which encourages young people to learn from each other armed by their inevitably limited perspective, while not engendering in them a discernment for the true and the noble, we will raise a generation who do not love learning but simply see the screen as a source of opinion that will suit their point of view without testing their veracity.

"Job prospects as well as personal happiness will be hampered by inadvertent statements - by themselves or others - and the marketplace in which juicy news is exchanged for the hard currency of street cred or the thrill of foolhardy fame will have done its worst."

More than 500 million people currently use Facebook to keep in touch with friends, share photographs and videos and post regular updates of their movements and thoughts. A further 145 million have signed up to Twitter.