Parents have spoken to the Newcastle Herald following the incident last term, concerned that other teens might be taking part in the potentially life-threatening practice.

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The students squeeze each other’s necks until the point of almost passing out but then tap each other on the arm to tell them to stop.

Choking creates a brief feeling of euphoria brought on by cerebral hypoxia, when the brain is deprived of oxygen for a short period.

Students were caught participating in the ‘‘game’’ at Belmont High on May 31.

A NSW Education Department spokesman said four students willingly took part in an incident, three actively and one passively.

‘‘They were given warnings and counselled about the dangers, and formal suspension cautions were given to the three active participants,’’ a spokesman said.

He said no students were injured or lost consciousness in the incident.

One parent, who did not want to be named, said he was concerned by the practice.

‘‘At one stage they were doing it every day,’’ he said.

‘‘It’s ridiculous they don’t realise how stupid they are, they don’t know what damage they can do.’’

He said his child had witnessed a game at the school where one participant passed out but said it was not brought to teachers’ attention.

‘‘He just came to and wondered what had happened,’’ he said.

The Newcastle Herald first reported on the practice in 2009 when a man, 19, was taken to hospital with serious facial injuries after playing the game at Stockton.

There were reports from Hunter teens it happened at parties and school toilets and had proliferated via the internet.

The game has been blamed for at least 82 deaths since 1995 in the US.

A 2008 Canadian study found 79,000 students in one province had tried the act.

The Education Department spokesman said the practice had not been raised as a major issue with the senior student welfare officer and encouraged people to report cases.

John Hunter Hospital emergency department director Dr Mark Lee said the practice could kill.

‘‘They are preventing oxygen from getting to the brain, which can lead to irreversible brain damage and even death,’’ he said.

Adolescent psychologist Emma Gallagher from NewPsych said while ‘‘choking’’ may seem strange to adults it was another example of young people engaging in risk taking behaviour.

While working in high schools she had seen teens try to brand themselves with cigarette lighters and said there was a new craze where they burnt crosses into themselves with salt and ice.

She said the behaviour was the result of a combination of teens having underdeveloped brains, testing boundaries and desperately wanting to be accepted.

‘‘When you put those together in group situations sometimes it can be a melting pot and it can spark this silly behaviour.’’