Internet companies are being urged to crack down on pupils posting inappropriate content as part of the drive against bullying.
Education secretary Alan Johnson called on the "big companies" running websites to meet their "moral obligation" and ensure material showing teachers or children being bullied is not posted on line.
He argued that this would help "blunt" the appeal of "cyber-bullying", which sees anonymous videos recorded using mobile phone cameras appearing on the internet.
"Cyber-bullying is cruel and relentless, able to follow a child beyond the school gates and into their homes," Johnson told delegates at teaching union NASWUT's annual conference in Belfast.
Although new technology opens doors, he warned that some teachers consider leaving their jobs because of this "online harassment", which amounts to "defamation and humiliation".
"The new powers allow teachers to confiscate mobile phones which film them maliciously but I believe there is a wider responsibility upon the providers of the sites which broadcast this material," he said.
He added: "Without the online approval which appeals to the innate insecurities of the bully, such sinister activities would have much less attraction.
"I am therefore calling on the providers of these sites to take firmer action to block or remove offensive school videos, in the same way that they have commendably cut pornographic content."
The "sinister downside" of "digital anonymity" can also put children in danger, he said, as it "provides a cloak for paedophiles who masquerade as children".
Mary Bousted, general secretary of the Association of Teachers and Lecturers, said: "We are particularly pleased at the secretary of state's quick response to demands from ATL that the growing problem of cyber-bullying in our schools and colleges be tackled.
"We now urge mobile and internet providers to keep to their side of the bargain and better protect our members from this type of bullying by providing easily accessible complaints procedures to register concerns and ensure that this growing problem in our schools is stamped out," she said.
