The SNP leader will say that Nationalist MPs returned to Westminster will introduce a bill designed to safeguard the health service “from ever being harmed by a Tory-Trump trade deal” if the Conservatives retain power at next month’s poll.

It was revealed yesterday that NHS bosses fear hospitals and patients would have to pay billions more for drugs as the price of Boris Johnson striking a post-Brexit deal with the US President.

But the UK Government has insited that “the NHS is not, and never will be, for sale to the private sector, whether overseas or domestic”.

Nicola Sturgeon will officially launch the SNP's 2019 election campaign in Edinburgh today

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Ms Sturgeon has pledged that the SNP manifesto will include a commitment to bring forward an NHS Protection Bill, which the party claims would explicitly prevent any future UK Government from signing up to any agreement that made the NHS, in any part of the UK, a bargaining chip in future trade deals.

The Bill would also give “a double-lock” by requiring the explicit approval of the Scottish Parliament, as well as the Welsh and Northern Irish assemblies, before any trade deal could be confirmed.

Each devolved nation would have to agree that any deal would have no negative impact on their National Health Service before any future UK Government could agree a deal.

Speaking ahead of her party’s launch event in the capital, Ms Sturgeon said: “A vote for the SNP is a vote to escape Brexit and to give people in the Scotland the chance to choose a better future as an independent country so we never have to worry about our NHS being sold off by a Westminster government.

“The NHS in Scotland is run in Scotland, for Scotland and under the SNP it will always be in public hands. Our NHS is not for sale at any price.

“And while the Scottish Parliament has control of health policy, we cannot currently stop Westminster signing away that protection in a trade deal, or entering agreements that dramatically push up drug prices or risk our public services, including the NHS.

“Boris Johnson has been very clear about his desire for a post-Brexit trade deal with Donald Trump – and no one should underestimate the threat which that poses.

“So in order to deal with that immediate threat from the Tories’ post-Brexit plans the SNP will bring forward a bill that would protect the NHS across the whole of the UK from ever being harmed by a Tory-Trump trade deal.“All parties say they oppose including the NHS in trade deals – so I challenge every party to today commit to backing this bill, and stopping the Tories trading our NHS for trade deals with Donald Trump.”

Meanwhile, the Conservatives today pledged to make it easier for medical professionals to move to the UK from around the world in order to provide care in the NHS.

An NHS Visa will be part of the new Points-Based Immigration System (PBIS), which the UK will be able to introduce because we are leaving the EU. It will be designed to restore control over immigration and attract the skills the UK needs.

General election 2019: Nicola Sturgeon pledges to protect NHS ‘across the UK’