The O2 mobile phone network crashed on Wednesday night, leaving thousands of customers across the UK cut off.

London - The collapse of the O2 mobile phone network caused chaos in the system for monitoring thousands of criminals in Britain wearing electronic tags.

Offenders may have got away with breaching the terms of their curfews while parts of the network were down.

Two companies, G4S and Serco, are paid around £100-million a year for monitoring some 24,000 offenders at any one time who wear an ankle tag and must comply with a curfew.

A box in the offender’s home uses the O2 network to communicate with a control room and issues an alert if they are not there when required.

The box also operates as a phone allowing monitoring staff to call in person to check if an offender is at home.

An insider at Serco said the collapse of the O2 network meant the system was “compromised” and staff were unable to call criminals to check where they were.

The source said: “Because the system was compromised, we don’t know whether it was reporting back correctly.

“Just as O2 doesn’t know how many people were affected, we don’t know how many people were affected.

“The back-up is to send someone physically to check but that was just impossible.”

The Ministry of Justice said around 250 offenders on G4S tags were affected by an “intermittent signal”.

But it insisted disruption was “minimal” and public safety was not compromised.

Serco said problems with O2 “did not affect our ability to detect breaches of curfew”. - Daily Mail