A £670 million-a-year plan to provide free social care will be paid for by cutting spending on research and development and public health promotions, as well as efficiencies in the NHS, Health Secretary Andy Burnham said.

But the Department of Health said the NHS's health research programme - including work on healthcare priorities such as cancer and dementia - would be "ring-fenced" to be protected from any cuts.

Research and development savings will come from the department's separate R&D budget, which concentrates on administrative issues, said a spokesman.

The Social Care Bill is a key plank of the Government's agenda set out by Gordon Brown in last week's Queen's Speech, which the Prime Minister hopes to rush on to the statute books in the maximum six months left before a general election.

It will guarantee free personal care at home for up to 280,000 elderly and disabled people with the highest needs, while another 130,000 will receive other help, including adaptations to their properties to allow them to remain at home for longer.

Mr Burnham told The Times he planned to pay for the measures by diverting £60 million from his department's R&D budget and £50 million from public health promotions.

Cutting spending on management consultants would provide £60 million, while further funds would come from a productivity drive intended to secure £20 billion in efficiency savings across the NHS over the next four years.

But a Department of Health spokesman said: "We can categorically state that cancer and dementia funding will not be affected. We are now providing more funding than ever for health research. This £1 billion budget is ring-fenced for research."

Mr Burnham said he would be "ruthless" in finding funding for the home care plan.

"It's always a question of priorities," he said. "I'm not cutting into vital projects. I'm moving stuff out of lower-priority, backroom spend towards direct public benefit."