Education secretary Alan Johnson has stepped up the fight against so-called cyberbullying by telling web providers they have a "moral obligation" to remove videos of people being ridiculed or bullied.
In a speech to the National Association of Schoolmasters Union of Women Teachers (Nasuwt) conference in Belfast, Mr Johnson stressed that both teachers and pupils need to be protected from online harassment.
"Cyber bullying is cruel and relentless, able to follow a child beyond the school gates and into their homes," he said.
He is also urging websites like YouTube and RateMyTeachers to block videos and offensive messages directed at teachers, citing examples of some teachers quitting as a result of such harassment.
"The online harassment of teachers is causing some to consider leaving the profession because of the defamation and humiliation they are forced to suffer," he added.
"These are big companies we are talking about: they have a social responsibility and a moral obligation to act."
Nasuwt general secretary Chris Keates said the matter had to be "taken seriously".
"The problem is that it's very difficult to regulate the internet and also these sites such as...YouTube and Rate My Teacher...all allow children to hide behind anonymity, where the teachers are named, they're exposed to ridicule, insulting comments, and subjected to false and malicious allegations," she told the Today programme.
"And it's important first of all that anything that can be done to trace pupils that use them in this way is done, and sanctions [taken] against them.
"But I think we've also got to look for improved redress for victims of these sites if the sites won't regulate themselves."
Patrick Nash, the chief executive of the Teacher Support Network, echoed such sentiments but warned that tackling the problem will be "challenging".
"We are pleased that the secretary of education is taking the issue of cyberbullying seriously," he said.
"Evidence from our recent survey with the ATL [Association of Teachers and Lecturers] shows that the impact of this kind of bullying can lead to lack of confidence and self esteem, feelings of anxiety and fear, with some teachers having to take time off work through stress."
When adding comments to the RateMyTeachers site, users are warned to keep their postings "appropriate" and told that "vulgar or profane" messages and those involving name-calling will be deleted.
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