THE DECISION to axe one of the region's prisons may have been a mistake, a watchdog has warned the Government.

Last month's closure of HMP Northallerton - rated one of the country's best - is questioned in a report by the National Audit Office (NAO).

The 252-place prison, built in 1783, is one of four being closed by next March as part of Ministry of Justice (MoJ) cost cutting measures.

The NAO warns that high-performing prisons are being shut, only to be replaced by new jails where standards are far lower.

"The strategy has resulted in the closure of several prisons that were performing well and their performance has not yet been matched by new establishments."

Amyas Morse, the NAO's head, said: "The Agency urgently needs to improve new prisons and look at ways to close fewer high-performing ones in future.

"The new larger prisons are bringing economies of scale, but the Agency does need to understand the consequences in terms of performance of building very large prisons."

Juliet Lyon, director of the Prison Reform Trust, told The Northern Echo: "It is disappointing the decision to close a small high performing prison like Northallerton appears to have been made on economic grounds alone.

"This seems to be to make way for a few super-sized prisons across the country, yet there is no evidence that titan jails will be safer or more effective at reducing reoffending."

Mark Robson, leader of Hambleton District Council, said: "It was a big shock to us, not only to hear it was to close but also at the speed in which it closed."

The NAO report noted that HMP Northallerton - which employed 190 people, including 138 Prison Service staff - had the highest possible performance rating of '4' by the National Offender Management Service Agency.

And it received a mark of '14' of a maximum 16 in a 'healthy prison' test run by HM Inspectorate of Prisons.

Since 2010, other high-performing prisons have been axed - while two of the three newest jails received "negative reports from inspectors".

The MoJ decided to ignore performance in deciding which prisons to cull, because "this would reduce the savings made".

The four jails to disappear by next year, with a loss of 1,400 places, will be replaced by a 2,000 inmate "super-prison" in North Wales.

The decision was a body-blow for Northallerton following the closure of the nearby Rural Payments Agency and Natural England office, which will see 400 posts relocated.

North Yorkshire County Council - based in Northallerton - has shed more than 1,300 jobs in the past three years while North Yorkshire Police has unveiled plans to move its headquarters from nearby Newby Wiske.

The NAO conceded it was "understandable" that the MoJ had focused on saving a total of £211m by 2015-16.

And the new prisons provided "good, modern accommodation, with safety features that reduce the risk of self-harm and suicide".

But it warned: "Decision-making has sometimes traded good quality and performance for greater savings."