Channel 4 documentary Dispatches, which broadcasts tonight, is set to reveal information about a series of meetings held between "senior civil servants and representatives of US pharmaceutical firms" where it claims, the price the NHS pays for its drugs was discussed.
NHS staff and health campaigners have raised fears the US government and its pharmaceutical industry want the NHS to pay more for their drugs, which are already far more expensive in the US.
According to a series of tweets made by the Dispatches programme there have been six official meetings between British trade negotiators and their US counterparts to discuss a future trade deal.
"Precise details of what has been discussed has been kept strictly confidential. But a Whitehall source has told us that drug pricing has been on the table in all six meetings."
The source also allegedly told Dispatches that US drugs firms have been given direct access to British trade officials. "Dispatches has been told that as well as meeting with the US government, senior British trade officials have held face-to-face meetings with representatives of US drug firms, none of which have been declared.
"Our source also told us that there have been five secret meetings between senior British civil servants and the US pharma industry. Two in Washington and three in London."
The programme also reveals that British trade officials have been warned that the subject is so sensitive that they must not mention “drug pricing” in emails but use the term “valuing innovation”.
Reacting to the revelations, Scotland's health secretary Jeane Freeman, said: "Secret indeed. Meetings that the Scottish Government have not been informed of - far less had any influence over and which directly affect our NHS in Scotland.
"The Tory UK government is not only displaying contempt for Scotland, our government and our parliament but now our NHS. Time to get them out."
She added: "The only way we can be sure to stop this and protect our NHS from Tory trade deals with Trump or Brexit damage is to get Johnson out of office and win Scotland’s independence."
According to the programme-makers, when they took their allegations to the UK government, a spokesperson for the Department for International Trade said: “The sustainability of the NHS is an absolute priority for the government.
"We could not agree to any proposals or medicines pricing or access that would put NHS finances at risk or reduce clinician and patient choice.”
According to Al Jackson, a partner at public relations firm Portland’s Washington DC office, Amercian pharmaceutical companies "are keenly interested in using a potential bilateral trade agreement to amend the health technology assessment process relied upon by NICE and the NHS to set drug prices in the UK.
"President Trump has complained about European nations "freeloading" on much higher US drug prices, suggesting that Americans are underwriting much of the cost of research and discovery while Europe benefits from government-negotiated lower prices.
"The Pharmaceutical Research and Manufacturers Association (PhRMA), the drug company lobby in the US, has urged government trade representatives to include changes to the health technology assessment process, valuation and pricing."
And in the documentary, one of Donald Trump’s former top trade negotiators, Stephen Vaughn, said he does not understand what Mr Johnson means when he says the “NHS is not on the table”.
The former general counsel for the Office of the US Trade Representative, said: “That that really goes to the question of what the UK government means when it says the NHS is off the table. I don’t know what they thought they meant when they said that. “
Until April this year, Mr Vaughn was the top lawyer in the Office of the US Trade Representative and a key player in recent trade deals with Canada, Mexico and South Korea which saw the US win key concessions over the price those countries paid for US medicines.
Mr Vaughn said: “I would expect US negotiators to see what we could do in terms of getting increased access to the British market. That’s what we do… I think it’s going to be likely to come up because the US mentioned pharmaceuticals in its negotiating objectives”
The programme focuses on the drug Humira, used to treat 46,000 patients in the UK who suffer from diseases like rheumatoid arthritis and Crohn’s disease, made by US drugs company AbbVie.
It is the single most expensive drug for the NHS costing £450m a year. Last year, the NHS started prescribing cheaper alternatives to Humira that will save the health service £150m a year.