Over-50s could be forced to pay more than £300 a year extra National Insurance to help fund a fairer social care system under plans drawn up by senior Tory Damian Green.

The former Cabinet minister argues that the care system should adopt the model of the state pension, with everyone entitled to a basic "safety net" of support, but individuals are encouraged to top up this provision from their own savings or housing wealth.

Mr Green, who was in charge of drawing up the Government's long-awaited green paper on social care for England while he was in government, also set out a range of measures aimed at filling a £2.75 billion funding gap - including a potential 1% National Insurance hike on over-50s.

In his Fixing the Care Crisis paper, drawn up for the Centre for Policy Studies, Mr Green suggests that the National Insurance hike is a "last resort".

An extra £350 million could be generated by taxing the winter fuel allowance - and stopping it altogether for higher rate taxpayers - and funding could also be found by diverting savings from elsewhere in government.

If required, the 1% levy on National Insurance, which would mean an extra £308 a year for the average taxpayer between 50 and 64, would raise £2.4 billion.