A shortage of nursing staff is hindering delivery of a comprehensive mental health service at a prison, inspectors have found.

Inspectors said that much has been done to improve the situation at HMP & YOI Grampian in Peterhead since its standard of health and wellbeing was graded as "poor performance" following an inspection in November and December 2015.

However, they said that the enduring shortage of mental health nurses was "of particular concern" and suggested that Aberdeenshire Health and Social Care Partnership and NHS Grampian may need to consider alternative ways of delivering care in the prison.

HM Inspectorate of Prisons for Scotland (HMIPS) made a return visit to the prison in June 11-13 this year to assess what progress has been made since 2015.

The report said that despite the staffing issues, there has been a striking improvement in the morale of the healthcare team since the last inspection, with staff stating that they now enjoyed working in the establishment.

HMIPS said: "What was immediately evident on our return was the effort that had been made by Aberdeenshire Health and Social Care Partnership and HMP & YOI Grampian to address the concerns raised in 2015.

"An increased staffing complement had been agreed following the 2015 inspection. However, the healthcare team was still operating with fewer permanent staff than deemed necessary.

"Of particular concern was the enduring shortage of mental health nurses, an issue that we understand affects the wider NHS Grampian Board area.

"Given that the shortage of mental health nurses has existed for a number of years, and appears to be a Board wide issue, it may be that Aberdeenshire Health and Social Care Partnership and NHS Grampian needs to consider alternative delivery models for mental health services within HMP & YOI Grampian."

The report noted that the ability to deliver a comprehensive mental health service "continued to be hindered" by not having the full complement of nursing staff.

HMIPS added: "Although there is still considerable work to do, inspectors saw demonstrable evidence of how the actions taken since 2015 had had a positive impact on the service being delivered."