Former Tory minister Liam Fox received a £20,000 donation earlier this year from a Covid-19 testing company that he reportedly contacted the former health secretary over.
According to an email seen by the BBC and the legal campaign group the Good Law Project, Dr Fox recommended SureScreen Diagnostics to then-health secretary Matt Hancock in 2020.
SureScreen Diagnostics would later be awarded a £500 million testing contract by the Department of Health and Social Care.
The £20,000 donation to Dr Fox, a former defence secretary, is contained in the MPs' register of interests and was recorded as being received in June 2022.
According to the BBC, a SureScreen director emailed former GP Dr Fox in June 2020 to tell him that the company was sending "millions of antibody tests" to use in hospitals in Germany, Spain and Sweden.
The director also complained it was "crazy" the tests could not be used in the UK, due to a lack of approval by Public Health England.
The BBC reports that Dr Fox forwarded that email to Mr Hancock, the health secretary at the time.
It is not clear if anything resulted directly from Dr Fox's email, but several months later SureScreen was awarded a contract for a different type of antigen test.
A spokesperson for North Somerset MP Dr Fox said: "This is a baseless smear concocted by the political activist Jolyon Maugham and the Good Law Project. It is appalling that this should be propagated by the BBC.
"Dr Fox will be making a formal complaint to the BBC and is taking legal advice on the matter."
Mr Maugham is the executive director of The Good Law Project, which has sued the Government over its use of emergency powers during the pandemic to agree contracts without opening them to competition.
In a statement to BBC, SureScreen said: "The donation to Dr Fox's office - not Dr Fox personally - was made by one of the directors of the business. This donation was specifically to support a series of events which include education talks from expert guests.
"The payment is not connected in any way to lobbying."
Mr Hancock denied any suggestion of wrongdoing.
A spokesperson for Mr Hancock said: "All DHSC (Department of Health and Social Care) contracts are decided, priced and signed off by the civil service, who are independent of Mr Hancock.
"If Mr Hancock received an email about expanding testing, of course he would have acted on it irrespective of the source.
"Not to do so would have been completely irresponsible. Remember: what was happening at the time was a national effort to expand testing, and all this uncovers is people working together to save lives."
A Department of Health and Social Care spokesperson said: "All testing suppliers - including SureScreen Diagnostics - were evaluated before contracts were awarded, in line with stringent procurement regulations and transparency guidelines.
"Tests supplied by the UK Government also underwent a rigorous scientific evaluation process before distribution to make sure they were highly effective at detecting Covid-19."
