SCOTTISH ministers have warned UK Work and Pensions Secretary Iain Duncan Smith that NHS services are coming under "intolerable strain" due to the extra workload created by welfare reforms.

The letter sent by Deputy First Minister Nicola Sturgeon and Health Secretary Alex Neil states the high number of successful challenges following fitness-to-work decisions – with 37% of the 39% who appeal winning their case – suggests there is something "seriously wrong" with the assessment processes.

It notes the demand on GPs, who have seen a rise in requests from patients for medical information to support appeals, is creating a "workload problem", particularly for practices with a large number of benefit claimants.

It states: "We are also aware some GPs do not provide information as the only fair way to manage an intolerable demand on them. This creates an inequity for those being asked to obtain information from their GP. We would recommend that the DWP undertakes urgent research on the demands that welfare benefit reform is placing on claimants and primary care."

The letter raises concerns the introduction of the bedroom tax and new assessments for personal independent payments will "place even greater burdens on GPs in the future".

Last month, the Sunday Herald reported how worried patients were asking GPs for letters to help avoid the bedroom tax, by confirming they need someone to stay overnight.

In February, the DWP announced a fourth independent review of Work Capability Assessments would be undertaken by Dr Paul Litchfield, BT's chief medical officer.

The letter to the UK Work and Pensions Secretary adds: "We would hope that after this review you are able to produce an assessment that is fair, equitable and that can get it right first time for the client.

"We urge you to put the acquisition of relevant medical evidence at the heart of the review to relieve the intolerable strain that is being put on our primary care services."

Yesterday, it emerged that the BMA local medical committee in Glasgow has advised GPs not to respond to requests for reports to support benefits, saying doctors are not in a position to "administer nor to police the benefits system".

Dr Alan McDevitt, chairman of the BMA's Scottish General Practitioners Committee, said: "The BMA has been arguing strongly for the benefits system to be altered so it works effectively, rather than doctors being approached for additional information that puts increased pressure on their workload. There is a real danger that if the number of requests continues to increase, there will be a detrimental effect on patient care and we have taken every opportunity to highlight these pressures to both the Scottish and UK Governments."

Last night, a spokeswoman for the Scottish Government said it had not yet received a response to the letter. A DWP spokesman said Smith would respond to the letter "in due course".