Donald Trump has claimed that "thousands of people are marching in the UK" because the NHS "is going broke".
The US President criticised the UK's healthcare system as he targeted Democrats pushing for a British-style universal health system.
He tweeted: "The Democrats are pushing for Universal HealthCare while thousands of people are marching in the UK because their U system is going broke and not working.
"Dems want to greatly raise taxes for really bad and non-personal medical care. No thanks!"
The tweet has already had thousands of retweets and likes.
The Democrats are pushing for Universal HealthCare while thousands of people are marching in the UK because their U system is going broke and not working. Dems want to greatly raise taxes for really bad and non-personal medical care. No thanks!
— Donald J. Trump (@realDonaldTrump) February 5, 2018
Mr Trump's remarks come after demonstrations on Saturday near Downing Street, which saw protesters demanding more money for the NHS.
Demonstrators marching through central London carried placards emblazoned with the words "kick the Tories out" and "more staff, more beds, more funds".
The NHS in Crisis march was organised by the People's Assembly and Health Campaigns Together.
Health Secretary Jeremy Hunt has since hit back at Mr Trump in a reply to his tweet.
He wrote: "I may disagree with claims made on that march but not ONE of them wants to live in a system where 28m people have no cover.
"NHS may have challenges but I'm proud to be from the country that invented universal coverage – where all get care no matter the size of their bank balance."
Labour leader Jeremy Corbyn responded: "Wrong. People were marching because we love our NHS and hate what the Tories are doing to it. Healthcare is a human right."
I may disagree with claims made on that march but not ONE of them wants to live in a system where 28m people have no cover. NHS may have challenges but I’m proud to be from the country that invented universal coverage – where all get care no matter the size of their bank balance https://t.co/YJsKBAHsw7
— Jeremy Hunt (@Jeremy_Hunt) February 5, 2018
Responding to Mr Trump's tweet as his party released a report into healthcare reform in the UK, Lib Dem leader Sir Vince Cable told Sky News the NHS was not "broken" but "under enormous pressure".
"If he wants to understand how the system works in Britain and wants some solutions he should come and read our report," said Sir Vince before adding that the US leader "obviously doesn't understand it (the NHS) but I live in hope".
The President's tweet comes amid Government plans to charge migrants twice as much to use NHS services, raising millions for the health service.
The health surcharge for those from outside of the European Economic Area (EEA) seeking to live in the UK for six months or more will result in up to £220m extra funding.
The Department of Health said the fee will increase from £200 to £400 per year with a discounted rate for students and those on the Youth Mobility Scheme, rising from £150 to £300.
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Speaking of the move, health minister James O'Shaughnessy said: "Our NHS is always there when you need it, paid for by British taxpayers.
"We welcome long-term migrants using the NHS, but it is only right that they make a fair contribution to its long-term sustainability."