Tens of thousands of offenders will be released from prisons in England and Wales wearing tags that track their location in real time as part of the biggest expansion of electronic tagging in British history, ministers have announced.

The prisons minister, James Timpson, said a new pilot scheme would track domestic abusers and stalkers, alerting authorities if they approached their victims, while other offenders will wear geolocation tags that will enable probation officers to track their live location.

Under the plans, the vast majority of ex-offenders leaving prison will be tagged under a “presumption … as part of intensive supervision with the Probation Service”, but probation officers will have fewer meetings with “low-risk” prisoners to focus on the most prolific and high-risk offenders such as terrorists, murderers and prolific sex offenders.

“This is the biggest expansion of tagging in British history and means the most dangerous offenders will now be watched more closely than ever before,” said Lord Timpson.

The government has taken the dramatic move after an overcrowding crisis in prisons, which last year saw tens of thousands of prisoners released early under an emergency government scheme. Launched in September 2024 – after prisons almost reached full capacity – the scheme saw about 40,000 prisoners released over a 12-month period, according to Ministry of Justice figures, released after a freedom of information request by the BBC.

Last year an official watchdog warned that the probation service had “too few staff” with “too little experience and training”, which left members of the public at risk. The public accounts committee found that longstanding staff shortages had left probation staff dealing with “excessive and unmanageable workloads”, with officers working at 126% of capacity for several years in some areas.

The prison service only met 26% of its targets for timeliness of appointments and delivery of services in 2024-25, down from 50% in 2022, according to the National Audit Office. The MoJ said that between 2023 and 2025, 31% of target probation appointments did not take place.

The MoJ said it would recruit 1,300 extra probation officers in the next year, as part of a £700m investment by 2029, which will include £100m for the tagging expansion by the end of this parliament. The department said “proximity monitoring technology” for domestic abusers and stalkers would be tested in a £5m pilot.

Tagging, while a “useful option” as part of licence conditions combined with supervision and support, was “not a panacea for reducing reoffending”, said Pia Sinha, CEO of the Prison Reform Trust.

The charity was sceptical about the move, she said. “It’s hard to monitor, and could lead to more breaches and possibly recalls,” she said. “Equipment is not always reliable and also can prevent genuine resettlement and rehabilitation of offenders because the tagging is over-restrictive.”

The victims’ commissioner, Claire Waxman, said moves to rebuild the probation service were welcome, but while tagging could provide a sense of reassurance she had spoken to many victims who believed their perpetrators were tagged when they weren’t.

“Technology and innovation are only as effective as the system that supports them,” she said. Tagging must be backed by swift enforcement the moment a breach occurs or there is a real risk of creating a false sense of security for victims.”