Voluntary carers who spend more than 50 hours a week looking after loved ones would be guaranteed a week’s break under plans announced by the Liberal Democrats.

Around one million people would benefit from the proposals, the Lib Dems estimate.

Carers would receive a “personal budget” equivalent to the cost of a week’s residential care, allowing them to take a seven-day holiday or series of smaller breaks while patients are looked after elsewhere or by other people.

Mr Clegg will set out his party’s “respite care guarantee” in a speech to health think tank the King’s Fund.

The future of social care - for people who need help with basic needs like washing, dressing and eating - has been the subject of bitter political feuding in recent weeks.

Secret cross-party talks on the creation of a national care service broke down in acrimony, and on Friday the Tories boycotted a conference to discuss the issue amid fears that Labour is planning to introduce a compulsory £20,000 levy - dubbed the “death tax” - to pay for reforms.

There have also been concerns about the funding of government plans to provide free personal care to 400,000 of the most vulnerable people in their own homes, under the Personal Care at Home Bill currently before Parliament.

The Lib Dems have said they would scrap the bill and use the £420m set aside for it by the Department of Health to fund the respite guarantee, along with a further £100m already allocated for respite care.