Teenagers at a St Albans school have been warned against playing a dangerous game which involves holding their breath until they fall unconscious.

Verulam School teachers felt they needed to intervene after some pupils started to copy a trend on social media known variously as the ‘Pass-Out Challenge’, ‘Space Monkey’, ‘The Choking Game’, or ‘Suffocation Roulette’.

To complete the challenge, teenagers deliberately hyperventilate until they lose their breath and feel light-headed, then a friend compresses their lungs by pushing on their chest, making them faint.

Variations on the fainting-inducing game have been around since the mid-90s, but it recently gained popularity on social media after videos of teens completing the challenge went viral.

But, players are unaware they risk causing themselves serious damage or even death - as when they pass out the brain is starved of oxygen, which can cause seizures, brain damage, comas, and in worse cases can prove fatal.

In September 2012, a 15-year-old boy playing the game fell forwards onto a glass and cut his neck, losing so much blood that he later died in hospital.

He had been copying instructions on the game from a YouTube video when the accident happened.

An assembly was given to students at Verulam to warn them about the challenge.

Head teacher Paul Ramsey said: “During the final week of last term, we became aware that a very small number of pupils had attempted to copy a trend they had seen on social media.

“The ‘Pass-Out Challenge’, in which people attempt to make themselves momentarily pass out, is clearly a worrying trend.

“We immediately addressed the issue during assemblies in the final week of term and made it clear how potentially damaging this can be. We have informed parents and I am pleased to confirm that we have had no further instances of this occurring in the school.”

This latest trend comes after the Blue Whale game gained popularity in Russia - this is a social media game which encourages teenagers to take their own lives, and has been linked to more than 100 teen suicides.