The world's largest social media site, Facebook, repeatedly refused to remove an offensive photograph casting a slur on a Co Limerick teacher, according to the school.
Facebook told staff at Colaiste Chiarain, Croom, that it did not believe the photo violated its standard on bullying and harassment.
Twenty-eight students were suspended for two days for "liking" an online posting that featured an image and text concerning the teacher's personal life.
School principal Noel Malone described it as a "gross invasion of a privacy" and a serious case of cyber-bullying.
The case has put a focus on the difficulties faced by schools trying to deal with the growing incidence of cyber-bullying.
Principals are frustrated that reporting a problem on social networks, such as Facebook, involves sending an email, rather than making phone contact. Mr Malone said there should be a "hotline" to ensure that schools can have such incidents dealt with immediately.
He said, if necessary, either the Department of Education or Department of Communications should have a liaison person whom schools could contact and who, in turn, could insist that offending material was removed.
The Department of Education launched a national anti-bullying plan in January but it does not include provision for a hotline.
Mr Malone said the offending material had been brought to his attention on Thursday by other students and he was "absolutely horrified" that a member of the school community would be subjected to this treatment.
He said they made repeated contact with Facebook over a weekend with a view to having the material removed and got a number of emails back saying it was not in contravention of their policy.
The 28 students have since apologised to the staff member and Mr Malone said they were "in bits" when the full implications of their action was spelled out to them.
Mr Malone said they did not know who posted the material.
"We are not sure if it was a student within the school or a past student or somebody completely from the outside but we are looking to find that out.
"There is an electronic footprint for everybody and we have fairly sophisticated technology and are doing our best (to find out who post the image)."
He said the posting was removed by someone unknown on Monday afternoon, about 15 minutes after he began the disciplinary process.
Mr Malone said he was heartened by the response of those involved, most of whom will have returned to school by today.
All but one set of parents agreed with his action and he said the victim was also satisfied with the outcome.
A Facebook spokesman said offensive content in breach of Facebook rules is quickly removed after it is reported.
Facebook safety director Patricia Cartes recently told the Irish Independent that the company prioritises all complaints from juveniles and, in particular, those involving allegations of cyber-bullying.
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