A 13-year-old boy was airlifted to hospital after slipping 100ft down a steep drop.

The boy was on a school orienteering exercise at Cow Gap, near Beachy Head, when the accident happened yesterday.

First reports suggested he had fallen over cliffs but a spokeswoman for his school, St Bede's Preparatory in Eastbourne, said: "It was a steep grass slope.

"The boy suffered a badly bruised shoulder and he was being kept in hospital overnight for observation."

The spokeswoman said there was no issue surrounding supervision.

She said: "The boy was on a properly organised orienteering outing with six members of staff. He slipped on a bit of grass."

The accident happened just six weeks after ten-year-old James Black, from Eastbourne, plunged 80ft over cliffs near Beachy Head.

He too was airlifted to hospital, where he was treated for a head wound.

James landed on a mound of rocks at the base of the cliff west of Holywell. At the time his mother, Penny, said: "A guardian angel must have been watching over him. You never hear of anyone falling down the cliffs and surviving."

Yesterday's accident happened at 11am.

An ambulance arrived but technicians Russell McCombie and Liz Smith were unable to reach the boy in their vehicle.

The Sussex Police helicopter was called in and landed at the bottom of the hill.

The technicians made their way down the slope to the boy while helicopter paramedic Paul Winsor made his way up from the bottom.

An ambulance service spokeswoman said: "Remarkably, the boy appeared not to have suffered serious injuries, apart from his shoulder, and he was conscious throughout.

"With the help of police officers the ambulance staff were able to safely move the boy on to a spinal board and carry him to the waiting helicopter at the bottom of the hill."

Mr Winsor said: "Given the distance he had fallen, remarkably this boy appeared not to have suffered serious injuries."