Appearing visibly angry, she accused Mr Corbyn of resorting to "fake claims, fear and scaremongering" over the impact of her plans and chided reporters who asked about a dementia tax for "using terms that have been used by the Labour Party to try and scare people in this country".
The ads are likely to have cost hundreds of pounds, but the exact price will depend on how many people click on them - the more that click, the more the parties will have to pay.
But she was repeatedly challenged over the social care issue, with the Liberal Democrats accusing her of "panic" while Labour leader Jeremy Corbyn said her Government was mired in "chaos and confusion".
Under the current law, the expenses of people living in residential care are met by local authorities and recovered from the sale of the family assets after death.
In 2015, 43 per cent of 18-25 year olds voted Labour, and 55 per cent of those registered in the 2017 General Election intend to vote Labour.
Announcing the cap in Cardiff Monday, Mrs.
Speaking at the launch of the Welsh Conservative manifesto, Mrs May refused to be drawn on the specific amount of the upper limit but said it would be part of a wider consultation.More news: FBI deflects House Oversight Committee's request for documents
Former Chancellor George Osborne, who now edits the newpaper, tweeted the story. Osborne, sacked by May after the European Union referendum, was first to break the story of May's reversal on the policy.
"It looks to have been ruled out, if not explicitly, then very much implicitly and lo and behold, it suddenly changed and a cap has been added in the last few hours, it seems".
However, the main factor underpinning the pound's strength since the early election call has been the expectations that May will win an increased majority in parliament, giving her a stronger negotiating hand when the United Kingdom and the European Union formally start Brexit talks on June 19.
A Survation telephone poll published on Monday showed May's lead halving to 9 percentage points, with Labour up 5 points and the Conservatives down 5.
May had sought to poach traditional Labour supporters with a mix of pledges more radical than those of her predecessor, David Cameron.
In nationwide polls conducted last week, the Tories' lead over Labour has been slashed to single digits.
The Labour Party is fighting back in Wales and is predicted to win the majority of seats there after overtaking the Tories for the first time since the snap General Election was called, according to a new poll.
ICM's director, Martin Boon, said polling over the weekend had "indicated a resurgent, if still rather distant Labour party" and "reinforces the impression that Labour have won the short-term manifesto battle". The latter remained under pressure, failing to register any meaningful gains against the Canadian dollar and the yen and falling 0.27% and 0.22% against the Swiss franc and the Australian dollar respectively.