A reduction in health research and development, public health promotions and consultants will pay for the government's free social care proposal.

Health secretary Andy Burnham has used an interview with the Times newspaper to set out how he will pay for the £670m-a-year plan to provide free social care to people in their own homes.

He said £60m would be found from the Department of Health's research and development budget, and a department spokesman has clarified that this relates to money for administrative matters. The £1bn funding for health research in areas such as cancer or dementia would be ringfenced, he said.

Burnham also said £50m would be found by cutting spending on public health promotions. The Tories have pointed out that this would affect campaigns on problems such as MRSA, obesity and sexually transmitted diseases.

The government plans to access another £60m for the policy by reducing the use of management consultants, and another £20bn would be produced thanks to efficiency savings across the NHS over the next four years.

The secretary of state has insisted that he will not be taking funding from vital projects. "I'm moving stuff out of lower-priority, backroom spend towards direct public benefit.

"All I want to say is we are being tough about that. I'm interested in really squeezing so that we get as much benefit directly to the public as quickly as we can.

"I've got to be ruthless about that and I will be ruthless about that."

The Social Care Bill, to be published today, guarantees 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.

However, the plans have been criticised by opposition and Labour politicans. Labour peer Lord Lipsey of Tooting Bec, a former member of the Royal Commission on Long-term Care, has questioned whether the money could be found through efficiency savings.

He told GMTV: "I have not seen the bill yet, but if it does what it is reported to be doing, the first thing is that it is extremely expensive. We really have a very tight position fiscally nationally now, this is an extra £670m in year one - in Scotland, where they have done this and it has proved a disaster, that sum rose by three quarters in just four years.

"So taxpayers are going to have to pay for this for years and years and years."

This is not a well-crafted policy because it only helped those who were able to stay at home. "If they have to go into a home because they have got really advanced dementia or are doubly incontinent, all those horrible things that happen at the end of life, they won't get a penny of extra help from the state as a result of this bill," he said.

Shadow health secretary Andrew Lansley has also questioned Burnham's sums, claiming that they "simply don't add up".

"The amount of money they are cutting from the NHS budget doesn't even begin to cover what they claim the cost of the policy will be, which most experts agree is already a gross under-estimate," he said.

"Labour are also proposing to axe key public campaigns on areas like tackling MRSA, obesity and sexually transmitted diseases.

"Many people will wonder if this is the best use of NHS resources."