Phone jamming technology should be deployed in prisons to end a £9m a year trade in illegal mobiles behind bars, a watchdog at Britain's largest jail said.
David Jamieson, chairman of Wandsworth prison's Independent Monitoring Board, warned inmates are able to used smuggled-in phones for drug dealing, bullying and to fuel gang problems.
But he accused the government of "pussyfooting around" the issue amid concerns it is expensive and complicated.
He said phones can be sold for as much as £400 each inside and the trade was worth £9m in 2008.
Some 7,000 phones were seized last year but the number in circulation could be three times that, he warned.
While almost impossible to stop them getting inside, Mr Jamieson said signal-blocking technology would render them useless, preventing prisoners from using them to co-ordinate crime and intimidate witnesses on the outside.
He said: "The technology... does exist. It would cost about £250,000 to equip a prison to jam calls. That would pay for itself quite easily over time."
Mr Jamieson said ever-smaller handsets allow phones to be easily smuggled in by prisoners, visitors or corrupt staff, while others are simply thrown over the wall.
But the Prison Service said signal blocking is technically challenging and not quick, simple or cheap to implement.
A Ministry of Justice spokesman said it was already an offence to smuggle a phone into prison and that a new bill included laws intended to make it illegal to possess one in jail, with a penalty of up to two years.
He added: "The objective of this clause is to act as an additional deterrent to those who consider trafficking a mobile phone and/or its component
parts into a prison, or to have them in their possession and to punish those who do."
Telegraph
