A major criminal gang ran a £30m drug smuggling operation from their cells using laptops provided by the Ministry of Justice, a new report has said.

According to The Independent inmates were given the laptops to help them prepare for legal cases, but instead organised a shipment of one tonne of heroin and ketamine to Britain.

The gang were even said to have paid £1m to persuade a "fixer" to get himself convicted of fraud and sent to HMP Wandsworth, in London, to help conduct the operation.

The criminals were supposed to use the computers as part of a taxpayer-funded scheme to help them get ready for their cases, but the machines were hacked. Security features were disabled by a gang member identified as an "east European hacker", who used a code contained on a memory stick smuggled into the jail by one of the gang's girlfriends penetrate the prison's security firewall.

A corrupt prison officer is also said to have provided the gang with a mobile phone to help them sneak the drugs into Britain from south Asia in holdalls hidden in shipping containers.

Prisons are 'overcrowded and understaffed'

Labour shadow prisons minister Jenny Chapman told The Independent that the incident was "an extremely serious breach".

"This needs an immediate investigation and it's rather symptomatic of the system in its current state," she said. "We cannot allow inmates' access to equipment that should be a privilege to be abused in this way.

"They have to step up their efforts to prevent this type of abuse. Overcrowded and understaffed – these are just the kind of security breaches we find when staff are working under pressure."

Despite the worrying breaches of security, the Ministry of Justice has not stopped the Access to Justice scheme.

In response to the story published by Sky News, a Prison Service spokesman said: "Prisons are required to provide secure laptops to a minority of offenders facing trial, so they can view legal material relating to their case.

"The computers do not enable prisoners to access any other part of the National Offender Management Service system and internet access is disabled.

"We will always take action against those attempting to break the rules and offenders face prosecution if they use equipment inappropriately."