Thousands of patients living with incurable pain are being let down by the Scottish NHS, according to a hard-hitting report by the health service's own watchdog.

Despite four official investigations in the past 14 years highlighting worrying gaps in care, the research reveals there has been very little improvement.

Specialist support for people who suffer chronic pain is patchy and inadequate, patients are confused and clinicians are frustrated, say the authors.

They are demanding action from the Scottish Government and health boards to ensure patients, who can wait years for the treatment they need, get faster access to the right medical help.

It is estimated that 18% of the population, 900,000 people, suffer some form of chronic pain. This is discomfort from injury or disease which persists beyond the typical healing process.

One-quarter of people diagnosed are unable to continue working because of the condition, yet just 3% of sufferers are sent to the specialist clinics.

NHS Quality Improvement Scotland, which monitors standards in the health service, has published the latest report.

It notes the Scottish Office first described services as patchy in 1994 and further documents published by very experienced people in 2000, 2002 and 2004 raised the same issues.

"Despite all of this, very little progress has been made. Access to specialist services is poor."

NHS QIS found not one health board could accurately describe the services they did offer.

Dr Pete Mackenzie, who worked on the report, said: "There are major blackspots around the country where there is almost a complete lack of service. The chances of (being told there is no hope) are much greater if you live in an area like that."

Dr Mackenzie said, there was frustration about the pace of progress, adding: "It is fair to say many of us, and particularly the patients with chronic pain, feel reports come and go and nothing much happens."

A Scottish Government spokeswoman said: "We are considering the recommendations relating to the Scottish Government, and the Health Secretary will use her address to the national conference organised by the Pain Association Scotland on May 20 to set out her response.

"We have for a number of years been encouraging the development of a managed clinical network approach to chronic pain."