"Immediate action" is being taken after blueprints of jail layouts were shared online.
The maps detailing the layouts of prisons in England and Wales were leaked on the dark web over the past fortnight, according to The Times.
The detailed information is said to include the locations of cameras and sensors, prompting fears they could be used to smuggle drugs or weapons into prisons or help inmates plan escapes.
Security officials are now working to identify the source of the leak and who might benefit from the details.
The Ministry of Justice did not disclose which prisons were involved in the breach.
A government spokesperson said in a statement: "We are not going to comment on the specific detail of security matters of this kind, but we are aware of a breach of data to the prison estate and, like with all potential breaches, have taken immediate action to ensure prisons remain secure."
The leak comes amid a chronic prison overcrowding crisis, which has led to early release schemes and the re-categorising of the security risks of some offenders to ease capacity pressures.
Justice Secretary Shabana Mahmood is launching a sentencing review in a bid to ease the crisis.
(c) Sky News 2024: 'Immediate action' taken after blueprints of prisons in England and Wales leaked on dark web
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