The running of private prison HMP Kilmarnock has been transferred to the Scottish Prison Service after its contract with Kilmarnock Prison Services Ltd came to an end.

The jail was previously run by private contractor Serco, and the move comes as the prison estate has been under heightened scrutiny in recent months over concerns about its fitness for purpose and overcrowding.

Chief Inspector for Prisons for Scotland Wendy Sinclair-Gieben said this week that HMP Barlinnie in Glasgow was at risk of “catastrophic failure”, while HMP Greenock should be “bulldozed” – although she did praise the relationships and staff at the latter jail.

Scottish Prison Service chief executive Teresa Medhurst said HMP Kilmarnock was “well run” and had “long-standing links to its local community, and a determination to deliver the best possible outcomes for those in its care”.

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She added: “The strong relationships underpinning the prison are a credit to the senior leadership team and staff who work there, and have undoubtedly contributed to its overall success.

“The transition of HMP Kilmarnock has been a unique and momentous responsibility for all involved, and I am grateful to those in SPS, Serco, and KPSL who have worked tremendously hard to do so successfully.”

Mark Whittaker, the justice business managing director for Serco, said everyone at the firm was “immensely proud of our track record”, adding: “Not only has Killie provided a safe, decent environment for the prisoners who have spent time there, but it has also been the most cost-effective prison in the Scottish estate and made a massive impact on the lives of the prisoners in our care”.

Mr Whitaker also thanked staff at the facility, saying they were “an extraordinary team of people who have done a challenging and demanding job with professionalism and compassion”.

“We are sad to see them leave the company and wish everyone all the best for the future,” he said.