Terrifying moment teenager lay under a railway line as train sped by - just inches from his head

The stunt is filmed by a friend on a mobile phone while a group of youths can be heard in the background shouting encouragement.

Police are now examining the footage - which has been viewed by over 700,000 people on a file-sharing website - and condemned the prank as "madness".

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A spokesman for British Transport Police said: "Behavior such as this obviously extremely dangerous.

"Trains certainly can't swerve to avoid people so to actually lie under a railway line is sheer madness.

"Not only is this person putting his life at risk but he's also risking the lives of anyone on the train." The clip involves at least three boys with Irish accents who appear to be aged around 17 at an unidentified train station.

Headlined "Really stupid Stunt" on the site www.break.com, the footage lasts one minute and 46 seconds. It begins with the prankster - called 'Pikey' by his mates - lying in a 5ft-long gap underneath a railway sleeper.

On several occasions he pokes his head and hands up directly into the path of the oncoming train just moments before it passes.

At one point an older teen, who sounds like the cameraman, warns 'Pikey' to stay down because there is a train approaching.

He yells: "Get down, like. Pikey, this is it now man. Keep your head down, like. S*** my heart's beating, like. Keep your hands down, man." Later, another teen shouts: "Make sure the video gets it."

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As the train screams overhead one hooligan shouts: "Pikey you mad b******, you mad man." After the train passes, one of the teenagers jumps down onto the train tracks to congratulate his pal.

The youngster, dressed in a blue sweatshirt, punches in air in celebration as he emerges from underneath the track.

Safety experts condemned the prank and criticised video websites for showing such footage which could spur potentially deadly copycat attempts.

Roger Vincent, of safety campaigners the Royal Society for the Prevention of Accidents, said: "This kind of thing is totally ridiculous.

"Those children are putting their lives at risk by playing on a railway. Train tracks are not playgrounds, they are potentially very dangerous places.

"By filming it, they are trying to glorify these acts and while they're posing for the camera, their attention is not on looking out for trains.

"If the site operators can do anything about it, they should, otherwise other people will copy them, will potentially fatal results." The risky stunt is the latest in a line of controversial clips posted on YouTube and other video websites.

People have died or have been arrested after attempting stunts of the type commonly found on the internet.

In a 'car surfing' incident last month, a man aged 18, from Chesterton, near Harbury, Warwickshire, died after falling from the roof of a Fiat Punto.

The car's female driver, also 18, was arrested.

In March, a man was arrested by Lothian and Borders Police in Scotland after a clip appeared on YouTube showing a Honda Fireblade speeding at 170mph on a wet day.

In another incident, Nathan Campbell, 18, was caught by police after filming himself driving at more than 140mph near Blackburn, Lancs., and was jailed for four months.

Jack Carroll, 22, was banned from driving for a year after taking a Warrior tank from a garrison and driving it over a car. A mobile phone video was put on YouTube.

The website which contained the train stunt footage was www.break.com. No one from the site was available for comment.