A drone transporting a large supply of contraband into a maximum security prison has crash landed inside the prison grounds.

Drones used to smuggle contraband

Drones used to smuggle contraband

Prison officers at Oklahoma State Penitentiary found a package containing a 5.3 ounce bag of marijuana, worth around £1,000 in Britain, 0.8 ounces of crystal meth, and one gram of heroin, after the drone clipped razor wire surrounding the prison and fell to the ground.

"I applaud and commend the quick action and diligence on the part of the staff who noticed the UAV [drone] entered the prison grounds," said Robert Patton, director of the Oklahoma Department of Corrections.

Officers also discovered a pair of hacksaw blades and a mobile phone within the package of contraband, destined to be sold inside the prison, where most of the 900 inmates are held under maximum security.

In Britain, the use of drones to evade security has reached "an all-time high", according to Glyn Travis, assistant secretary of the Prison Officers Association, with more than 10 drones crashing into British jails in just six months.

"It is an extremely worrying development as drones are inexpensive, easily accessible and you don't have to be a fighter pilot to fly one," said Mr Travis.

"They are used to transport contraband or as reconnaissance vehicles, looking for weaknesses in security.

"At a time of cost cutting and reduced staff numbers, it is hard to deal with this new threat."