Last year's total fell to �25m, prompting the SNP to ask why there has been such a significant reduction.

Something is definitely going on and I think we need an investigation to find out just exactly what.

SNP MSP Kenny Gibson

A recent survey of X-ray equipment inside the country's hospitals found that 40% were more than 10 years old.

Medical staff say that old equipment and the lack of new purchases is pushing waiting times for simple medical procedures higher and higher.

BBC Scotland found one case where a 10-year-old Glasgow girl, who had a stone in her kidneys, waited three months for an ultra sound scan.

SNP MSP Kenny Gibson believes trust hospital chiefs are using money which should be spent on new machinery to reduce budget deficits.

Kenny Gibson: Inquiry call

He said: "Labour's spin is that more and more money is being spent on the NHS in Scotland every year, but what we're actually seeing is nose-diving of equipment expenditure.

"Something is definitely going on and I think we need an investigation to find out just exactly what."

Deputy Scottish health minister Ian Gray said: "Certainly, the replacement and maintenance of equipment has an effect on patient care, but that's exactly why over the last year we've begun to reinvest in capital.

"Capital investment in the health service is increasing by �60m over a three-year period."

Long-term solution

He denied money was being diverted to plug holes elsewhere.

He said: "These are not equipment problems that can be changed overnight.

"This is not something that can be purchased immediately.

"For example, �12m invested in linear accelerators. Those accelerators need concrete bunkers constructed before the accelerator can be purchased."

Executive 'failed'

Last month, hospitals across Scotland received an �11m cash injection to fund either new or upgraded accident and emergency departments.

The Tories' health spokesman, Ben Wallace MSP, said: "The executive has singularly failed to manage resources sensibly.

"Instead of allocating any new monies into front line services, Labour and the Liberals have only succeeded in squandering public money on waste, inefficiency and bureaucracy."