A 14-year-old boy narrowly escaped serious injury when he crashed 20ft through the roof of a building.

The teenager and three friends had been playing on the flat roof of an engineering firm's premises in Portslade.

Police fear there could be a repeat of the incident during half-term week and today warned teenagers and children to avoid dangerous areas.

Acting Inspector Wendy Burton, of Hove police, said: "The teenager in this case was very lucky as he suffered only minor injuries but it could have been much worse.

"In light of the fact it is half-term week there is a chance that other children may try the same thing and climb other buildings.

"One of the more common areas this happens is at schools, where access can be easier.

"Fortunately most of the cases we deal with do not end in accidents but what has happened to this boy is a warning. Next time someone might not be so fortunate.

"These are not playgrounds and we are urging people to be sensible and stay away from them - otherwise we could find ourselves dealing with a tragedy."

Police were alerted by a member of the public on Saturday night who said four teenagers were on the roof of CP Mechanicals in Basin Road North, one of whom had fallen through.

Firefighters from Preston Circus in Brighton had to force their way into the building to reach the trapped youngster. He was taken to the Royal Sussex County Hospital in Brighton.

Luckily, the youngster suffered only minor cuts, scratches and bruises.

Firefighters said the roof of the building was made of plastic and also contained asbestos, which added to the danger.