The Prime Minister said it was "essential" that those people who worked hard and saved for their retirement were treated fairly in the provision of social care but he warned there was "no easy solution" to the problem.

"Of course, helping relatives is a challenge that most families rise to - however difficult it becomes," he told a breakfast meeting of leaders in the social care field, held at the King's Fund in central London.

"But that doesn't make it any easier. Nor does it remove family worries about providing physical care that is needed - or take away people's concerns that at some point in the future they may have to sell a treasured home to pay for their own care."

Mr Brown's remarks came as a six-month public consultation on how the state, families and taxpayers should tackle the future provisions and funding of social care was launched.

Figures released in a Government discussion document state that in the next 20 years the number of people over 85 in England will double and the number over 100 will quadruple. The document also says that advances in medical knowledge and practice mean disabled people can live longer and can lead healthier lives.

"We expect over 1.7 million more people to have a need for care and support in 20 years' time," the report said. "A radical re-think of the care and support system is needed to address these challenges."

Mr Brown said he "fully" understood people's anxieties over the issue of social care. "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," he said.

He said he wanted the system to be more responsive to demands for independence and it must be made easier for people to stay in their own homes. He said social care reform went to the "heart" of the Government's ambition to create a fairer Britain.

State support for social care is means tested and includes services such as help in cooking, shopping and caring for a family.