Donald Trump has triggered another spat with Theresa May's government after claiming the NHS was "going broke and not working".
Health and Social Care Secretary Jeremy Hunt hit back by saying he was "proud" of the British system despite the "challenges" it faced.
The US president made the attack as he targeted Democrats pushing for a British-style universal health system.
He said "thousands of people are marching" in the UK because of concerns about the state of the NHS.
But Mr Hunt responded to Mr Trump's Twitter attack with a post of his own, saying no-one protesting about the state of the NHS wanted a US-style system.
"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," he said.
Mr Trump's comments came shortly after former Ukip leader Nigel Farage appeared on one of the president's favourite US TV news shows to talk about the NHS.
Mr Farage's appearance on Fox And Friends appeared to be the reason for Mr Trump's Twitter comment.
In a follow-up message, the president thanked the show for "exposing the truth".
Mr Trump's social media messages came after a crowd of thousands chanting "Save the NHS" descended on Downing Street on Saturday to demand more funding for the health service.
Marching through central London to draw attention to the NHS funding shortage, people carried placards urging "Kick the Tories out" and "More staff, more beds, more funds".
The demonstration, called NHS In Crisis: Fix It Now, was organised by the People's Assembly and Health Campaigns Together.
Shadow health minister Justin Madders said: "The president is right to focus on Saturday's march in which thousands of people joined Labour in protesting eight years of austerity, which have drastically worsened patient outcomes and demoralised the workforce.
"A universal, publicly provided NHS free at the point of use remains the most cost-effective and efficient mode of healthcare provision, a fact the president would probably consider 'fake news'.
"In its 70th year, only Labour will ensure our health service stays true to its founding principles and a world class service for all."
Mr Trump is due to visit the UK later this year and faces the prospect of mass protests against his controversial presidency.
He had previously caused consternation in Whitehall when he announced on Twitter he would not be attending the opening of the new US embassy in London, saying it was a "bad deal" and he did not like the location of the new building.
It led to speculation he was unhappy after being rebuked by Mrs May for retweeting videos posted by the far-right Britain First group.
However, following his talks with Mrs May in Davos, Mr Trump reaffirmed his commitment to the "special relationship" with Britain.