Half of all patients believe they will have to pay for NHS treatment within 10 years, according to a survey carried out on behalf of doctors.

The British Medical Association study, released on the eve of its annual conference in Edinburgh today, found the majority of people believe the NHS should remain free but 50% also expect to have to pay towards services a decade from now.

One-fifth of those quizzed were from Scotland, where the devolution of health has increasingly eroded the notion of a national health service with Scottish Government decisions on NHS funding differing vastly from those made south of the border. Tomorrow, Scottish Health Secretary Nicola Sturgeon will address the 400 doctors from across the UK at the conference where she is expected to discuss those differences, which include the use of public-private finance deals.

Around half of the people who took part in the survey opposed the now predominantly English policy of encouraging commercial companies to provide NHS healthcare to patients, with almost two-thirds objecting to private firms making a profit from providing such care.

The Scottish Government shunned private funding for the new South Glasgow Hospital earlier this year because ministers said it was more expensive than 100% public funding.

The funding concerns raised in the survey back those of doctors who yesterday voiced fears that the ethos of the NHS could be destroyed by charges brought in "by default".

BMA council chairman Dr Hamish Meldrum suggested that public anxiety was fuelled by rising costs hitting health boards across the UK and by growing public-private partnerships south of the border. He said: "Although the public strongly supports the principles of the NHS and wishes to preserve it as a tax-funded system, they are clearly worried about the future funding of the health service and the government's direction of travel on health policy.

"It is possible that the English government's increasing use of the commercial sector in providing NHS services is fuelling patients' concerns that the NHS will begin to charge for some care in the future.

"The public may also fear that, with rising drug and treatment costs, advances in medical technology and increasing demand for services, the NHS will no longer be able to afford a completely comprehensive health service."

Repeating the BMA's long-held view that ministers should launch a debate about what the NHS can provide, he warned: "It would be a travesty if, by default, charges were introduced, destroying the ethos of a universal and equitable healthcare system that is valued by patients and admired across the world."

He also called on UK governments to reassure the public that it intends to maintain a tax-funded health service, "not just for the next 10 years, but for the foreseeable future".

The research follows controversy over people who opt to pay for certain drugs which they cannot get on the NHS in their area being charged for the rest of their related care as a result.

The BMA survey canvassed the views of more than 1000 people, in Edinburgh, London and Bristol. Two in five respondents felt changes to the NHS in the past 10 years had brought improvements for patients.

A Scottish Government spokeswoman stressed it was committed to the core principles on which the NHS was founded, as demonstrated by its pledge on abolishing prescription charges.

A spokeswoman for the Department of Health at Westminster echoed that commitment.