Alan Johnson today signalled his support for a new form of social care insurance as he launched a national debate on future support services for the elderly.

Although the health secretary insisted that there was no "blueprint" for the scheme, he said people wanted certainty that care would be provided.

"If we are running out of so-called free personal care – which even the Liberal Democrats have dropped as a commitment – then you are looking at some kind of insurance that can be provided by the state or the individual," Johnson told reporters.

Johnson, who spoke at the launch of a six-month public consultation on how individuals, families and taxpayers might be expected to share the costs of providing a satisfactory service, stressed that he was "a long way" from a solution. "We want a proper debate," he said.

The Department of Health estimates that the cost of maintaining the current, often inadequate, level of personal care services is set to double to more than £24bn in 2026 as a result of rapid growth in the number of frail older people.

Without new sources of funding, the government expects "a £6bn funding gap for social care" to emerge within 20 years.

The problem is understood to be regarded in Whitehall as possibly the most serious challenge to public services over the next 20 years, during which the number of people over 85 is likely to double and the cost of disability benefits is expected to increase by 50%.

The prime minister, Gordon Brown, has asked Johnson to prepare a green paper on how services can be improved without imposing an unsustainable burden on taxpayers.

In a speech today, Brown said: "We know too many people fear the prospect of selling their homes and using assets which otherwise they would pass on to family members and friends [to pay for care in old age] ... We can, and must, look to give people the opportunity and the support to save for their old age in a way which insures them and protects their houses and their inheritance."

Under the current system, many local authorities ration care for people who need help with getting dressed, washing, shopping, cooking and eating, leaving tens of thousands struggling to carry out the daily routines of living. Means-testing obliges people going into care homes to pay expensive charges if they have savings of more than £21,500.

Johnson said he wanted a new system that promoted independence, choice and control for people who need support. It should also be "affordable for government, individuals and families in the long-term".

He added: "There is no option of a quick fix. Radical change is needed ... so that people are clear about what they are entitled to and where they can get it."

The Department of Health announced a £31m experiment in "telecare" services in Kent, Cornwall and the London borough of Newham to monitor people living at home with long-term medical problems and allow them to summon help if their condition deteriorates.

The scheme was designed to let people live longer in their own homes and reduce emergency admissions to hospital. The experiment will test whether the costs of installing hi-tech equipment in people's homes are outweighed by savings for the NHS and welfare services.

The government's move came as the British Medical Association published a poll of GPs showing that 80% think healthcare services for older people are not good enough.

Among a sample of 500 doctors, only 8% believed that care homes do enough to maintain residents' mental agility and physical fitness.
About 60% said there was not adequate continuity of care as people moved between the NHS and social services; and 62% said there were not enough services to support people with dementia.

Helena McKeown, a GP from Wiltshire and chair of the BMA's committee on community care, said: "It's disgraceful that care services are so chronically under-funded.

For example, cutbacks in my area meant I heard of elderly patients having their bathing reduced from twice a week to once a week, something which they found very distressing and dehumanising."

The Liberal Democrat leader, Nick Clegg, today described the treatment of older people as "a stain on the moral conscience of society" and accused the government of "11 years of delay and dither" over the social care crisis.

Clegg said: "Elderly people in desperate need of better care will now have to wait until the next election before any action is taken. This is totally unacceptable.

"This government has presided over a collapse in elderly services. Ministers have responded to the chronic warnings of a looming crisis only with criminal under-funding.

"The Liberal Democrats are still the only party to offer an immediate solution to this crisis. Our proposals for a 'personal care payment' would ensure a fair deal for all elderly people who need personal care and would put an end to the injustice of poor access to social care."

The chairman of the Local Government Association community wellbeing board, David Rogers, said there was a funding "black hole" because the government's financial support for councils had not kept pace with the demands of an ageing population.

Rogers said: "Social care budget increases have not kept pace with demographic changes, forcing councils to withdraw services for people with low and moderate needs, such as help with the cleaning and bathing.

"Local authorities are determined to give older people a fair deal, but the social care system is creaking at the seams.

"Ministers need to turn with urgency to the long-term overhaul of the future funding of adult care services. There remains a black hole in funding for the care of vulnerable people."