It was set up with the aid of cash from Fife benefactor Alf Stewart after his late wife Barbara had to travel to England for the treatment.

Mr Stewart himself died recently and his money has now run out.

However, that was only ever meant to be start-up funding and the hope was always that NHS Tayside would eventually take on full funding of the £90,000 per annum service, which it has now done from existing budgets.

Dundee-based MSP Marlyn Glen, alongwith other MSPs, believes it should be funded directly by the Scottish Government as patients come from all over Scotland for treatment, with patients from outwith Tayside funded by their own health boards.

The group of MSPs signed a motion in the Scottish Parliament calling on the Scottish Government to develop this service as a national managed clinical network, which was described as “providing a cutting-edge service in the treatment of diseases such as cancer”.

In her reply to Ms Glen, Ms Sturgeon said, “The referral of patients for photodynamic therapy from outside NHS Tayside remains a clinical decision, with the cost of the treatment for patients who are referred there being met by their own health boards, using well-established cross-charging mechanisms.

“I do not accept that direct Scottish Government funding of the PDT centre would be justified at this time. However, this position will be kept under review.”