Girl, 13, disappeared for three days and claimed to have done the dare

Involves vanishing without telling friends or family for up to 72 hours

French teenagers allegedly challenging each other to 'Game of 72'

An alleged Facebook game which sees children dare each other to vanish without a trace for up to three days is spreading panic among parents in France.

The dare, dubbed the 'Game of 72', involves teenagers challenging each other to disappear without a word to their families for 12, 24 or 72 hours.

Authorities have been alerted to the game after a 13-year-old girl from northern France went missing for three days last week.

Craze or fake? French police were alerted to the 'Game of 72' after 13-year-old 'Emma' went missing for three days last week, claiming she had done the dare

After being gone for 72 hours, the girl, names only as Emma, finally turned up safe and well at her family home at the weekend.

'Emma' then refused to tell police or her parents where she had been, but only said she had completed the 'Game of 72' dare.

However the 'Game of 72' is baffling authorities,The Local reports.

So far, police say, the only evidence is dozens of panicked Facebook posts being shared by parents, warning each other about the game, and Emma's testimony, to suggest the challenge exists.

The French group Against Dangerous Games for Children said: 'We urge all parents to be aware their children might be involved in this game.

Making it up? The 'Game of 72' is baffling authorities as the only evidence suggesting it is real is dozens of panicked Facebook posts being shared by parents and Emma's testimony

'Children must be told it is much better to fail the game, than risk a dangerous situation and never come home at all.'

Last year, French officials warned of another Facebook challenge for people to throw themselves into rivers or the sea or face buying a meal for the nominator.

The craze resulted in tragedy when a teenager drowned after tying his bicycle to his leg before riding into a river.