The family of a budding computer programmer have on Saturday launched a campaign to raise awareness about the health risks of playing online computer games after their son died following a marathon session on his Xbox.

A post-mortem revealed that 20-year-old Chris Staniforth -- who was offered a place to study Game Design at Leicester University -- was killed by a pulmonary embolism, which can occur if someone sits in the same position for several hours.

Deep vein thrombosis normally affects passengers on long-haul flights, but medical experts fear youngsters who spend hours glued to their consoles might also be at risk and have urged them to take regular breaks.

Professor Brian Colvin -- an expert on *la*hd-related conditions -- said it was "unhealthy" for youngsters to spend long periods in front of their consoles.

"There's anxiety about obesity and children not doing anything other than looking at computer screens," he told The Sun.

David Staniforth has now launched a campaign to warn other parents of the dangers.

"Games are fun and once you've started playing it's hard to stop.

"Kids all over the country are playing these games for long periods - they don't realise it could kill them," he told The Sun.

A coroner's court in Sheffield was told how the youngster -- who had no underlying medical conditions -- was complaining of a low heart rate before collapsing outside a Jobcentre.

Staniforth's distraught father said his son would spend up to 12 hours playing on his Xbox.

"He got sucked in playing Halo online against people from all over the world."

Online computer games are extremely popular as thousands interact in shared science fiction worlds.

Reports of gamers collapsing after spending 15 hours in front of video games are fairly common throughout Asia.

In 2005, a South Korean gamer died after playing online games for three days without taking a break.

Microsoft -- which manufactures the Xbox -- said it "recommend gamers take breaks to exercise as well as make time for other pursuits."