Theresa May fails to challenge Trump over attack on NHS after phone call with US President

No mention of Mr Trump's claim that the health service was 'going broke and not working'

Asked if the issue came up during the telephone call, Downing Street said: 'It did not.' (AP)

Theresa May failed to challenge Donald Trump after the US President mounted an attack on the NHS, describing it "broke and not working".

The two leaders shared a phone call about a new US law allowing American authorities to access data held overseas in order to tackle crime and terrorism.

However the Prime Minister did not raise Mr Trump's Twitter outburst against the NHS, where he claimed demonstrators took to the streets in London to protests against the British healthcare system.

The row comes after Ms May was criticised for failing to reprimand the President for re-tweeting propaganda footage from the far-right group Britain First, an incident that heightened tensions between the UK and the US.

While Ms May said he was "wrong" to promote the extremist videos, official reports of their conversation show she did not address the issue with Mr Trump.

Asked if the clash over the NHS came up during the leaders' call, Downing Street said: "It did not."

A spokeswoman said: "The Prime Minister spoke to President Trump this evening. They discussed the Clarifying Lawful Overseas Use of Data (Cloud) Act, due to be considered by the US Senate later this month.

"The act covers how the US can access data stored in another country, when it is needed to prosecute serious crime or to disrupt terrorism.

"It will also authorise the US attorney general to enter into agreements with like-minded allies like the UK to allow reciprocal compliance with US and foreign court orders.

"With it, law enforcement officials in the US and the UK will be empowered to investigate their citizens suspected of terrorism and serious crimes like murder, human trafficking, and the sexual abuse of children regardless of where the suspect's email or messages happen to be stored."

Ms May stressed the "great importance" of the legislation to investigating criminal and terrorist activity, which is "vital for collective security".

Earlier, Number 10 backed Health and Social Care Secretary Jeremy Hunt when he waded into the extraordinary Twitter row with the President over a demonstration in London on Saturday in favour of more funding for the health service.

Mr Trump said "thousands of people are marching" in the UK because of concerns at the state of the NHS, as he attacked Democrats pushing for a British-style health system in the US.

However Mr Hunt hit back, saying the US system left millions without adequate health cover and none of the protestors wanted a US-style health service.

"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.