Ministers have a “moral duty” to introduce a cap on costs of care for the elderly, a former Government advisor has said - suggesting it was “silly” to suggest reforms were unaffordable.

Sir Andrew Dilnot, who led a cross-party commission on social care, spoke out following political rows between the Cabinet about a long-delayed green paper on the matter.

Plans to tackle the issue nearly cost the Tories the last election, with proposed measures branded a “dementia tax”.

Theresa May has said a social care green paper, due within weeks, should introduce a cap on costs for any individual.

But last week the Health Secretary wrote to the Prime Minister saying he was concerned that a limit of £100,000 could cost £3.4 bn and mean significant tax rises.

Matt Hancock also highlighted Treasury concerns about a new system of insurance, which would see money automatically docked from monthly wage packets, to pay for care in later life, could hit pay packets too hard.

Sir Andrew yesterday urged ministers to press ahead with changes, almost eight years after his commission recommended a cap on costs.

He told The Telegraph: “There is a moral duty; we are letting people down in social care.