Health Secretary Jeremy Hunt was forced to deny that he had received warnings of EU nationals "fleeing the UK" if the country opts for a hard Brexit, after the phrase was spotted on a briefing note which he carried into 10 Downing Street.
The document, exposed to press photographers by Mr Hunt as he arrived for a meeting of Cabinet, appeared to be a crib-sheet for responding to expected questions from MPs.
But he did not repeat the phrase during a session of oral questions to health ministers in the House of Commons shortly afterwards, telling MPs only that he wanted to give the 150,000 EU nationals working in the NHS the opportunity to continue doing their "brilliant job".
And he later said on Twitter: "For avoidance of doubt I have never been advised or believed Brexit means people `fleeing UK'. I was anticipating a question along those lines from MPs at health orals - which is why the phrase appears in my briefing note."
Cabinet heard an announcement from Brexit Secretary David Davis that the crucial Repeal Bill, paving the way for Britain's withdrawal from the EU, will finally be tabled next week.
The bill will repeal the 1972 European Communities Act which took the UK into the EU's predecessor, the European Economic Community, and will transpose relevant EU law onto the UK statute book, so that it can then be removed or amended as the UK Parliament wishes.
But it is expected to face a rocky ride through Parliament over the coming two years.
Meanwhile, Downing Street indicated that Prime Minister Theresa May gave her blessing to a call from Mr Hunt and Business Secretary Greg Clark for continued close collaboration with the EU on the regulation of medicines after Brexit.
The EU's European Medicines Agency is currently based in London, but will leave the country after Brexit, creating uncertainty for UK-based pharmaceutical firms about the regulatory regime for drugs in future.
In a letter to the Financial Times, the ministers said: "The UK is fully committed to continuing the close working relationship with our European partners.
"Our aim is to ensure that patients in the UK and across the EU continue to be able to access the best and most innovative medicines and be assured that their safety is protected through the strongest regulatory framework and sharing of data."
If the Brexit talks fail to achieve the "desired relationship", the UK will set up a regulatory system that protects patients and "supports the UK life science industry", they said.
Mrs May's official spokesman confirmed that the letter was shared with 10 Downing Street "in the usual way" before publication.
And the spokesman said: "What they set out was that we are committed to the close working relationship we have with our EU partners and beyond that, everything else is a matter for negotiation."
Arriving at Cabinet, Mr Hunt was seen holding a note containing suggested responses to questions from MPs, including the warning that "Hard Brexit means people fleeing the UK".
In the event, he told the House of Commons: "The 150,000 EU nationals working in our health and care services do a brilliant job and we want them to continue doing it."
Around 9% of doctors and 19% of nurses in England are EU nationals, said Mr Hunt, adding: "We are still seeing doctors and nurses coming to the UK and we need to do everything on all sides of this House to reassure them that we see them as having a bright and vital future in the NHS."
But Labour MP Heidi Alexander, a former shadow health secretary, told him: "The truth is EU staff no longer want to come here. Doctors and nurses are leaving in their droves."
Meanwhile, the European Parliament's chief Brexit co-ordinator Guy Verhofstadt repeated warnings that Mrs May's proposal for a new "settled" status, short of full citizenship, for EU nationals living in the UK following Brexit would deliver "less rights" to the estimated 3.2 million individuals involved.
"It's clear that the system that is proposed by the UK side - this 'settled status' they call it - is in fact a new system with less rights, incorporated in the migration system in Britain," Mr Verhofstadt told a press conference in Brussels.
"That's something completely different. The European proposal is a continuation of existing rights, not only for the European citizens living in the UK, but also for the UK citizens living on the continent."
Efforts to build bridges with Brussels may have been dealt a blow as a recording emerged of Brexit minister Steve Baker calling for the EU to be "torn down".
In the 2010 recording, obtained by The Independent, Mr Baker can be seen telling an event organised by the Libertarian Alliance: "I think the European Union needs to be wholly torn down... That is actually impractical unless the whole people of Europe can be persuaded to rise up and vote for politicians who are prepared - in a moderate and consistent and principled and gentle way - to say that the European Union project has merely succeeded in raising economic nationalism to a continental scale."
Asked if Mrs May continued to have confidence in Mr Baker, who was appointed to the Department for Exiting the EU last month, the PM's spokesman said: "Steve Baker was appointed to the job on merit and the PM has huge faith in him working with his colleagues to deliver a successful Brexit that works for Britain and the EU."
Liberal Democrat chief whip Alistair Carmichael said: "Jeremy Hunt knows that Brexit will be a disaster for the NHS and it should be no surprise that the Health Secretary's team expect him to be challenged on this issue.
"We have already seen record levels of EU nationals leaving jobs in the NHS last year, and there has been a dramatic fall in the number of nurses from the EU registering to come and work in our health service since the Brexit referendum.
"This will exacerbate existing pressures on staffing in our essential NHS and social care services and risks threatening the quality of patient care."
Labour MP Chuka Umunna, a leading supporter of the Open Britain group, said: "Whether it was photographed by accident or design, this document hits the nail on the head – a hard, destructive Brexit will lead to more EU citizens who work in the NHS leaving our country.
"Indeed, the number of EU nurses leaving has already increased since the referendum, which is putting our hospitals under great strain.
"Jeremy Hunt needs to make that point forcefully to the Prime Minister."