The Ministry of Justice says that handsets smuggled into jails are being used by offenders to harass victims, organize gangs and deal drugs on the outside. It has already carried out trials of jamming equipment with cell phone jammer Antenna, which is illegal if used in public, and is about to give portable devices to some prison governors.

And next week the Government will back a Bill proposed by a Conservative MP that would allow the authorities to track mobile calls attempted by criminals as well as stop them getting through to their associates.

It follows a series of reports by officials and experts warning that phones are being used to plan crimes and smuggle drugs into prisons without UHF VHF Jammer blocking the signal.

“The presence of wireless telegraphy devices, in particular, illicit mobile telephones, presents serious risks to the security of prisons and the other institutions to which the Bill applies, as well as to the safety of the public,” according to notes on the new draft law written by the Ministry of Justice.