Middle-class pensioners are to lose benefits under Conservative plans to fund social care, Theresa May will announce on Thursday.

The Conservative manifesto will set out plans to begin means-testing winter fuel payments and to charge more people who currently receive free care in their own home.

The money saved from means-testing the annual heating handout, worth up to £300, will be used to help close the £2.8 billion social care funding gap.

The Conservatives will also pass legislation to ensure nobody has to sell their home to pay for their care during their lifetime, and new rules will allow pensioners needing nursing home treatment to keep more of their assets.

The flagship policy marks a gamble as it risks angering core older Tory supporters. David Cameron repeatedly pledged to maintain universal pensioner benefits, but Mrs May’s team believes that pensioners can no longer be fully protected from austerity.

On Wednesday it was unclear whether the Prime Minister would also abandon the so-called triple-lock, which guarantees a rise in the state pension every year.

Writing in Thursday's Telegraph, Mrs May defends the welfare cuts by saying she is prepared to “take the big, difficult decisions that are right for our country in the long term”.