More than 45 million hours have been lost by NHS boards as a result of staff ill health over the past four years, research has shown.

New figures reveal the number of hours lost to illness rose year-on-year from 11.4 million in 2014-15 to 13.1 million in 2016-17.

The data was obtained by the Scottish Liberal Democrats through freedom of information requests to health boards.

The party's health spokesman Alex Cole-Hamilton MSP said the "immense" pressures facing staff could be contributing to the rise.

His concerns have been echoed by Jackie Baillie, the Labour MSP for Helensburgh and Lomond, who said this was a clear sign of the increasing pressure that NHS staff are experiencing.

Ms Baillie added: “The SNP Government cannot keep expecting NHS staff to treat even more patients with fewer and fewer resources.

"The consequence of doing so is a strain on our NHS with longer waiting times and staff off ill as they struggle to cope.”

Mr Cole-Hamilton also took a swipe at the SNP.

He said: "The SNP Government has utterly failed to deliver a step change in mental health or provide the right levels of support for our NHS staff. The result is a spiralling bill of health problems.

"The tremendous pressure on health workers on shift is spilling over and affecting their quality of life.

"A recent survey by the Royal College of Nursing found that 40 per cent of nurses say money worries are making them lose sleep.

"More than 60 per cent said they are too busy to deliver the quality of care that they would like."

Mr Cole-Hamilton added: "The Scottish Government's workforce plan isn't up to scratch. Hundreds of posts are lying vacant for months on end. Nicola Sturgeon's decision to cut training places has come back to bite.

"SNP ministers have relied on the goodwill of NHS staff for far too long and the impact can be seen in their health.

"The Scottish Government must ensure that NHS staff get the support and resources they need to deliver the best possible care and that starts with proper workforce planning to ensure they are no longer overworked and overburdened."

In response, Health Secretary Shona Robison said the welfare of NHS staff was critically important.

She added: "Every health board is required to have policies in place and to comply with national policies on managing health at work, which includes mental health and wellbeing.

"The latest statistics show NHS Scotland sickness absence rates have fallen in the last decade from 5.55 per cent in 2007 to 5.20 per cent in 2017, and we're supporting boards to undertake local initiatives to further address the sickness absence challenge.

"We're also reviewing the NHS Scotland 'Managing Health at Work and Promoting Attendance' policies to address underlying issues and ensure that appropriate supporting mechanisms are in place for staff."