Under-pressure Peterhead prison has reported a massive rise in the number of staff days lost through sickness.
Sick days among staff at HMP Grampian remained relatively stable at between 3,600 and 3,800 a year between 2015 and 2017, but soared by 62% to 5,968 last year.
It represented the largest one-year percentage rise experienced at any of the publicly-run prisons in Scotland in 2018.
Across all Scottish Prison Service (SPS) sites, the number of days lost to sickness increased by 46% from 47,152 days in 2015 to 69,072 in 2018.
Of these lost days, the number which were related to mental health issues soared by 78% from 12,795 days to 22,714 in the period.
The figures have emerged just two weeks after a review by the Auditor General for Scotland found that HMP Grampian was operating with 34 vacancies for uniformed staff.
It also reflects concerns raised by inspectors in a separate report earlier this year, which blamed staff shortages for inmates being left in their cells for up to 23 hours a day.
Last night, Scottish Conservative shadow justice secretary Liam Kerr said: “Staff in jails across Scotland do a fantastic job, but they are under tremendous pressure.
“There have been shortages at HMP Grampian, which makes life even more difficult for those on the frontline.
“We can see from these figures that a large proportion of days off sick are down to mental health issues.
“This is hardly surprising, but should concern the SPS and the Scottish Government. It is vital that staff have all the support and resources they need to do the job properly.”
An SPS spokeswoman said: “SPS employs over 4,500 personnel. Absences are managed in accordance with our attendance and absence policies and procedures.
“The SPS greatly values the health and wellbeing of our staff and we support all our staff through any absence from work.
“Where an individual is absent due to depression, stress or anxiety there is an immediate referral to our occupational health advisors.
“All employees have access to Help Employee Assistance, the employee help service which can provide short term counselling.”