A man who skied nearly 200ft down the longest escalator on the London Underground has been condemned by police and transport officials.
He launched himself down the 196ft (60m) escalator at Angel Tube station and filmed the stunt.
The unidentified man then posted it on the YouTube video sharing website where it has received more than 100,000 hits.
Transport for London (TfL) urged police to take the "strongest possible action" against any similar offenders.
A TfL spokesman said: "This is a dangerous, stupid and irresponsible act that could have resulted in serious injury or death to not only the individual concerned, but other passengers."
A British Transport Police (BTP) spokesman described the skier's antics as "naive and reckless".
They urged the man to contact them so they could discuss the potential dangers of his stunt.
A BTP spokesman said the video was thought to have been recorded about a year ago.
He said under by-laws they could not prosecute after six months had lapsed.
If someone had been injured, they would still have powers to prosecute under criminal law, the spokesman said.
The video, filmed from the skier's head-mounted camera, shows him walking, going up the escalator, fitting his skis on and launching himself down at high speed.
The escalator was clear at the time but passengers on opposite conveyors can be seen looking on, bemused.
The film's producer said other people were not in danger as friends of the stuntman, a Norwegian national, had warned passengers away.