The government was accused last night by the royal commission on long term care for the elderly of "betraying" millions of older people by refusing to accept its recommendation of free personal care for those who are no longer fit to look after themselves.

In an unprecedented move, nine members of the commission, which reported in 1999, reassembled to condemn the government's failure to act.

They challenged ministers to explain why the demand for free services, such as help with washing, feeding and medication is unaffordable. They asked why a cancer patient gets comprehensive NHS care while people with Alzheimer's disease requiring intensive personal care are generally left to fend for themselves.

"It is ethically impossible to justify this distinction. Payment of care costs should depend on need, not diagnosis," they said.

The nine, led by Lord Sutherland of Houndwood, the commission's chairman, congratulated the Scottish executive for accepting the proposal.

But they added: "The situation in England, Northern Ireland, and Wales, where the state supports nursing, but not personal care (except on a tightly means-tested basis) is unstable and, if not dealt with in the near future, will implode."

The commissioners, including Sir Nicholas Goodison, a former chairman of the London stock exchange, Robin Wendt, a former senior official of the DHSS, and the writer Claire Rayner, said there were "huge ethical, conceptual and practical difficulties in distinguishing the nursing from the personal care of ill and disabled older people.

"Making entitlement to state support dependent on the type of carer rather than the nature of the care needed is essentially a producer-driven approach which puts providers before patients and their needs."

Free personal care could not be regarded as a free handout to the rich. It was "vital to meet a pressing need consistently identified by older people and the wider public".

People with capital of more than £18,500 got no state help with care costs, except in Scotland, and the financial position of older people was deteriorating after the recent changes in annuity rates and the decline in the value of pension funds.

The commissioners said their proposal would cost £9.1bn a year. This was affordable, given the many billions recently allocated to the NHS, and made good economic sense.

With an eye on the Labour conference, they appealed to MPs and organisations concerned with the care of older people to renew their efforts to promote the recommendations. "More than four years on, there has been no reasoned rebuttal of [our] core funding proposal on policy grounds," they said.

As part of the NHS plan in 2000, ministers said they would spend a similar sum on better intermediate care to help older people leave hospital as soon as they did not require continuous medical treatment. They agreed to provide free nursing care, worth up to £110 a week, for older people living on their own or in residential homes.

The Department of Health said last night ministers did not intend to change their position. "Seven out of 10 older people already get some or all of their personal care costs paid for by the state," it said.

"The government believes it is fairer to spend the £1bn cost of providing free personal care by improving services for older people who need them, enabling them to be more independent and to delay, or even avoid, the need to enter residential or nursing home care."