It goes on to say boards can make "reasonable" charges for parking as part of a planned approach to facilitating access to sites, and to cover the costs of car park provision.

Hospital bosses must also ensure there is a reasonable allocation of car parking spaces to allow patients and carers to attend clinics and appointments, including access for emergencies.

They must also provide spaces for staff and put arrangements in place for staff parking in line with good employment practice.

The boards must consider wider travel and access issues.

Schemes which impose uniform charges and conditions across a number of sites are not acceptable under the new guidance and boards have been instructed to publicise more widely concessionary parking and operate them more flexibly.

Ms Sturgeon said: "The review group has endorsed the view that in general, car parking at hospitals should be provided free of charge.

"It also came to the conclusion that a maximum charge should be set, and in order to protect against unnecessary or excessive charges in the meantime, I decided in December to introduce a cap of £3 a day, which boards should implement without delay.

"Evidence from a number of health boards shows that charging high daily rates is not the only way to discourage or control unauthorised parking and I agree with the group's recommendation that all other avenues should be explored before charges are introduced.

"I hope that this guidance reassures those staff, patients and visitors who have had concerns about parking charges, and that we see fairer, more affordable schemes in place across Scotland."

Ms Sturgeon's order to cap the fees at £3 a day was a slap in the face for Glasgow's hospital bosses.

She told them the rates they had imposed were were "too high for staff on low wages, for patients and for visitors".

NHS Greater Glasgow and Clyde said they could not comment until they had seen the full details of Ms Sturgeon's announcement.