Top Tory Jacob Rees-Mogg has become embroiled in a live radio spat with a doctor over whether no-deal Brexit will lead to deaths.
Campaigning neurologist Dr David Nicholl challenged the Cabinet minister to say what mortality rate he would find acceptable after October 31.
Dr Nicholl, from Birmingham, said he was involved in drafting the government's contingency plans Operation Yellowhammer before blowing the whistle "because I felt they were unsafe".
But Leader of the Commons Mr Rees-Mogg snapped at the doctor, telling him he was a "Remoaner" who was "fearmongering" on public radio.
The Tory hard Brexiteer fumed: "There are reserve plans to fly drugs in as necessary. This is a major focus of government policy.
"I think it's deeply irresponsible, Dr Nicholl, of you to call in and try and spread fear across the country. I think it's typical of Remainer campaigners and you should be quite ashamed, I'm afraid."
Dr Nicholl has repeatedly voiced concerns about no-deal Brexit and threatened in March to stand against his local MP, Chancellor Sajid Javid , in an election. He spoke at a Change UK event and tweeted in May urging people to vote for the new anti-Brexit party.
He attended a People's Vote march in London, according to local reports, and spoke out in April to the BBC to criticise the policy of keeping no-deal documents secret.
Separately, he was also involved in Amnesty's long-running campaign for the release of British citizen Shaker Aamer from Guantanamo Bay.
His call comes three years after Michael Gove , now the no-deal Brexit planning chief, infamously said "people in this country have had enough of experts".
Dr Nicholl phoned LBC to tell Mr Rees-Mogg: "I was actually involved in Yellowhammer and drafting the plans of mitigation for a no-deal Brexit in March.
"My question to you really, having being involved in writing the plans for mitigation and having whistleblown because I felt they were unsafe, is what level of mortality rate are you willing to accept in light of a no-deal Brexit?"
Mr Rees-Mogg replied: "I don't think there is any reason to suppose a no-deal Brexit should lead to a mortality rate. I think this is the worst excess of Project Fear.
"And I'm surprised that a doctor in your position would be fearmongering in this way on public radio."
The doctor protested: "I wrote the plans in mitigation".
Visibly rattled, Mr Rees-Mogg snapped back :"You didn't write very good plans if you hadn't worked out how to mitigate, had you?
"It's fortunate they are being written by other people now who are serious about mitigating rather than Remoaners."
Dr Nicholl said that claim was "incorrect" due to reports that royal colleges have still not been approached to update Yellowhammer documents.
He said "we don't know" the predicted mortality rate, but insisted people would die in no-deal "because of all sorts of problems - issues of access to drugs, the issue of radio isotopes - that have already been highlighted."
The Yellowhammer documents - presented to ministers a month ago and leaked to the Sunday Times - warned Britain faces possible food, fuel and medicine shortages in the case of a no-deal Brexit .
Government officials insist contingency plans have been improved since they were written.
