NHS Grampian has said it cannot hit a 12-week Scottish Government surgery target for every patient.

Operations are meant to be carried out within three months of diagnosis but the health board has been forced to prioritise the most urgent cases to cope with demand.

Earlier this year, NHS Grampian delayed and rescheduled a series of routine operations amid a shortage of nursing staff.

Health secretary Shona Robison has apologised to any patients affected by the latest problem and said the Scottish Government would provide extra investment.

An NHS Grampian spokeswoman said: "We are currently unable to see all elective surgical patients within the 12 weeks timescale set out by the Scottish Government.

"In light of this situation our first priority is to ensure the most urgent patients get treated promptly.

"Therefore we are in the process of implementing an elective classification system to ensure those patients waiting longer are those clinically most able to do so."

She added: "The classification is clinically led and covers all adult surgical services.

"We realise this will be disappointing news for those patients classed as able to wait longer."

NHS Grampian said it remained committed to meeting the government's targets and the current situation was "a pragmatic interim solution to maintain safety whilst current waits are longer than we would like".

Speaking on BBC Radio Scotland's Good Morning Scotland programme, Ms Robison said demand is growing "across the health service in Scotland".

She added: "It's not ideal - we would want all patients to be seen in a timely fashion and I would apologise to anybody who is having to wait a bit longer than we would want them to wait - but I think it's important that the capacity that we do have is used to treat those patients who most urgently need to be treated."