The UTU call comes following following the lock-down of a Co Londonderry school which received a threat from ‘clowns’ on Friday.
The PSNI also revealed they have received several reports of social media posts in which people have suggested dressing in clown costumes and going to other schools to scare students and teachers.
“No-body wants to be a party pooper and the season of Hallowe’en is all about ghosts and ghouls and things that go bump in the night – but there’s a line and when that’s crossed things can get downright sinister,” said Avril Hall Callaghan, General Secretary of the UTU.
“Schools, above all places perhaps, need to be islands of safety in a society when young people and children are facing unprecedented pressures whether from family life, school life, social media – whatever.
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“Of course there’s the thrill that goes with a bit of a scare, but sadly we live in a world where the kinds of outrages portrayed in films and books have all too often crossed that line into real life.”
In 1996, 16 children and one of their teachers died when a gunman opened fire in the Dunblane Primary in Scotland, while in 1994 six pupils in Sullivan Upper School, Holywood, were injured in a flame-thrower attack.
“We have seen tragedies take place in our schools and in schools in the US and elsewhere and it is perhaps the recollection of these incidents which makes these so-called crazy clowns so sinister,” continued Ms Hall Callaghan.
“I would urge anyone even thinking about posting information or threats on social media platforms to consider what they’re saying. Encouraging behaviour that has the potential to generate fear or indeed posting threatening messages can lead to a criminal record.
“What starts off as a stupid prank could end up in the ruination of a promising young life if a young person gets caught up in something that could jeopardise their future.
“I would urge common sense to prevail. Of course, enjoy Hallowe’en, but stay on the right side of the law.”