The proportion of NHS cash spent on mental health has dropped in Scotland, according to new research.

All but three health boards report cuts in the percentage of their budget dedicated to mental health services - even though it is one of the Scottish Executive's clinical priorities.

Dr Sean Boyle, senior research fellow with the London School of Economics and author of the study, said Scotland ought to refocus on this area of medicine.

However, the Scottish Executive said the figures did not reflect the extra money GPs and councils are spending on patients with mental health problems. The research was commissioned by the health committee of the Scottish Parliament.

Roseanna Cunningham, the committee convener, said: "There is a long-held perception that mental health care is something of a Cinderella service within the NHS which does not receive an appropriate level of funding. Dr Boyle's figures show that while there has been an increase in the overall spend on mental health provision across Scotland, it is worrying that the share of overall expenditure in this field has dropped. The committee is concerned that this may reflect a reduction in the priority given to mental health."

Dr Michael Smith, spokesman for the Royal College of Psychiatrists in Scotland, said the findings confirmed suspicions. He added: "The reason we think that it is an area worth investment is because of the enormous prevalence of mental health problems. It represents a third of GP presentations, a third of GP time and 40% of incapacity benefit claims at least."

Shona Neil, chief executive of the Scottish Association for Mental Health, said Scotland needed to look at how the money being spent was benefiting patients.

A spokeswoman for the Scottish Executive said the latest figures show spending on mental health by NHS boards grew from £640m in 2003-04 to £687m in 2004-05.