HUNDREDS of prisoners may have been released from jails following a flawed assessment of the risk they pose to the public, an SNP minster has admitted.

Ministers have been warned that an IT glitch could have led to criminals being released too early after hundreds of cases were wrongly graded with the wrong degree of risk.

SNP Justice Secretary Keith Brown said that 1,317 assessments had taken place where the risk scores “did not match” the final risk level that was calculated – with 1,032 of them completed or closed cases, dating back to 2012.

In 537 of these cases, an over-ride was applied by social workers based on “professional judgement”, Mr Brown said, leaving 495 cases which “appear to contain a risk level affected by the system error”.

There are also 285 open cases in which the fault has been discovered.

The Conservatives have warned that the “horrendous blunder” may have led to criminals being released too early. But Mr Brown stressed that in 150 of the open cases investigated so far, it has been found there is no evidence of “any public protection risk as a result of this system issue”.

The revelation means that up to 780 prisoners may have been released after the risk score error.

The Justice Secretary highlighted the technical error to the LS/CMI system which “supports risk assessment and case management for individuals with a history of offending".

Mr Brown said that after initial investigations were carried out in January, “it became apparent last week that this was an issue affecting other users of the system”.

He added: “The particular systems issue affects the display of information in the risk assessment part of the system. The numerical risk score value in some particular instances does not match the risk score level displayed by the system.

“A systems issue appears to be preventing any subsequent changes made to that risk level when new information has been entered."

Mr Brown said that as of this week, there were 103,394 assessments categorised as “live” and 24,000 “open cases in the live system”.

He added: “I am advised that from the work carried out over the weekend there were 1,317 assessments where the calculated score did not match the final risk need/level.

“Of those assessments affected, 1,032 relate to closed cases and 285 relate to open cases.“ Mr Brown said that in 537 of the 1,032 closed cases, an “over-ride has been applied” by social workers.

He added: “That means there will be 495 of those closed cases which appear to contain a risk level affected by the system error.

“The remaining 537 with an over-ride applied will need a case by case review to determine if the over-ride superseded any error.”

Mr Brown said that “officials have taken immediate action to review open cases that the justice system is still managing”.

He told MSPs that “work is ongoing to identity the specific cases affected", adding that "on Tuesday my officials issued details of the open cases and locations of those cases to users of the system asking them to specifically review risk levels and scores and take any necessary actions”.

Mr Brown added: “Officials are assembling returns from users of the system as they do so and, to date, 150 returns have been received and no users of the system, social worker or SPS, have advised the Scottish Government of any public protection risk as a result of this systems issue.”

The Justice Secretary also told MSPs that as part of investigations, it has emerged “there may be another area of risk scoring relating to alcohol /drug use that creates an error”.

He added: “Whilst the extent of this is not known, it is clear that it may affect the risk score.

“The initial evidence on the system as presently reported indicates that the score is likely to be higher rather than lower i.e. to overstate risk rather than understate it.”

Scottish Conservative shadow justice secretary, Jamie Greene, said: “This is a horrendous blunder that may have put the public at risk.

“It is scandalous that hundreds of criminals may have been wrongly released from prison when they should still be serving sentences.

“This is a grave error on the Justice Secretary’s watch no matter how he spins it."

He added: “He claimed that the public have not been put at risk but the reality is he doesn’t know yet. He has absolutely no idea if this mistake has resulted in harm to the public. That is shocking and unforgivable.

“We need to know urgently from the SNP how many criminals were wrongly released from prison early, and the government must now guarantee that no prisoners are released whose risk assessment is, or even might be, wrong.”