A Conservative government would consult on a possible cap on social care costs, Theresa May has announced.

The announcement comes as the Tories' opinion poll lead over Labour shrank amid public concern over manifesto proposals which were branded a 'dementia tax' by general election rivals.

It amounts to a significant concession after the Tory manifesto said proposals from the Dilnot Report on social care, which included a ceiling on the total amount any individual would have to pay, 'mostly benefited a small number of wealthier people'.

Speaking in Wrexham, Mrs May accused Labour leader Jeremy Corbyn of resorting to 'fake claims, fear and scaremongering' over the impact of her plans.

She said: 'This manifesto says that we will come forward with a consultation paper, a government green paper.

'And that consultation will include an absolute limit on the amount people have to pay for their care costs.'

At one stage Mrs May shook her head in disagreement as a reporter suggested she had performed a 'U-turn' on her policy.

Under repeated questioning about social care, her voice cracked and she became visibly angry, repeating: 'Nothing has changed, nothing has changed.'

Asked about the so-called 'dementia tax', she shook her head repeatedly, saying: 'I'm sorry, you are using terms that have been used by the Labour Party to try and scare people in this country.

'This is a system that will ensure that people who are faced with the prospect of either requiring care in their own home or needing to go into a home for care are able to see that support provided for them and don't have to worry on that month-by-month basis where the funding is coming from.'

Mrs May's climbdown came after a clutch of opinion polls showed Labour eating into her party's lead.

The latest, by Survation for ITV's Good Morning Britain, showed the Conservatives on 43pc, down five points on the previous week and nine points ahead of Labour who were up five on 34pc.

Over the weekend, ministers were adamant there would be no going back on the plans set out in the Conservative manifesto.

But Liberal Democrat leader Tim Farron vowed to mobilise a national campaign against what he called the 'dementia tax' because of the potential impact on sufferers of the debilitating condition.

Lib Dems launched an online 'scrap the dementia tax' petition at dementiatax.org.uk.

Responding to the climbdown, Liberal Democrat former care minister and North Norfolk candidate Norman Lamb said: 'This is Theresa May's manifesto meltdown. This is not strong and stable. It's panic and U-turn.'

Scottish National Party leader Nicola Sturgeon tweeted: 'PM not so strong and stable after all ... and can't be trusted to protect pensioners.'

Ukip economic spokesman Patrick O'Flynn said the new policy was 'wholly inadequate' and raised more questions than it answers.

Mr O'Flynn said a cap in six figures would be 'wholly unacceptable' and urged pensioners to put pressure on the Prime Minister to commit herself to a specific and lower figure.

'The Conservatives are in full meltdown on this issue,' said Mr O'Flynn.

'But just telling people they will consult on a cap on social care bills is not good enough.

'Older voters need to know and deserve to be told what that cap will be.

'At the moment the Tories could just announce after the election that it will be £250,000 or even £300,000.'

In a sign of how the issue had taken centre stage in the election battle, both Tories and Labour bought ads on Google which pop up when users of the search engine type in the words 'dementia tax'.

In a reflection of the party's concern at the tag being attached to its policy, the Conservative ad read 'The so-called 'dementia tax' - Get the real facts', together with a link to a party website.

Labour's ad linked through to a page attacking Mrs May's manifesto, with 'Tory threat to pensioners' at the top.

In an apparent sign of Mr Osborne twisting the knife on the woman who sacked him from the Cabinet, an Evening Standard editorial described her announcement as 'an astonishing U-turn' and said: 'It is not encouraging that the original proposals were so badly thought through.'

Denouncing a 'weekend of wobbles' leading to a 'hasty' change in tack, the editorial said: 'The Tory manifesto has only just come out, and already it is being rewritten. Now ministers will struggle to explain where the cap will be set, how much it will cost - and why the manifesto originally said that previous proposals for caps on care costs were unfair.

'Just as well, really, that this manifesto wasn't written on a tablet of stone.'