Jacob Rees-Mogg has been branded “absolutely disgusting” after likening a doctor warning of deaths after a no-deal Brexit to disgraced anti-vaxxer Andrew Wakefield.

The Commons leader angered MPs when he stepped up his war on whistleblower Dr David Nicholl, a consultant neurologist, after a bitter clash earlier this week.

“I’m afraid it seems to me that Dr David Nicholl is as irresponsible as Dr Wakefield,” Mr Rees-Mogg claimed.

“What he had to say, I will repeat it, is as irresponsible as Dr Wakefield in threatening that people will die because we leave the European Union. What level of irresponsibility was that?”

The highly-respected Dr Nicholl was asked, by the last government, to help draw up the devastating Operation Yellowhammer document, predicting shortages of medicines, food and fuel after a crash-out Brexit.

Dr Wakefield, meanwhile, was struck off the UK medical register for unethical behaviour after his discredited research linked autism to the measles, mumps and rubella (MMR) vaccine.

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The claim led to parents stopping their children being immunised and an increase in measles cases. The UK recently lost its measles-free status.

Sarah Wollaston, the former Conservative, now Liberal Democrat, MP said Mr Rees-Mogg would be sued if he had made the attack outside the House of Commons.

“Absolutely disgusting for @Jacob_Rees_Mogg to slander such a highly respected NHS consultant and whistleblower as @djnicholl from behind the cowardly screen of parliamentary privilege,” she tweeted.

Pressure on Mr Rees-Mogg grew when England's chief medical officer wrote to him to attack his “disrespectful” comments.

“As the government's chief medical adviser and England's chief medical officer, I feel compelled to express my sincere disappointment in the disrespectful way you spoke to and about Dr David Nicholl,” Professor Dame Sally Davies wrote.

“Comparing an established medical expert to a man who was struck off the medical register by the General Medical Council, and described by them as 'dishonest, irresponsible and showed callous disregard for the distress and pain of children' is going too far and is frankly unacceptable.”

The latest controversy comes amid growing criticism of Mr Rees-Mogg, whose behaviour has been blamed for fuelling the Tory civil war over Brexit.

He was labelled the “embodiment of arrogance, entitlement and contempt for parliament” after lying down on the Commons front bench during a key debate.

Some of the 21 rebels who sank Boris Johnson’s hopes of defeating the back-bench bill to block a crash-out Brexit said they ploughed ahead with their revolt because of him.

And Phillip Lee, when dramatically defecting to the Lib Dems on Wednesday, said Mr Rees-Mogg’s attack on Dr Nicholl had “tipped him over the edge”.

“It was disgraceful, it was about ignoring evidence, it was about showing disrespect to experts, to people with professional standing and knowledge,” Dr Lee protested.

In the clash on live radio, Dr Nicholl had asked the Commons leader: “What level of mortality rate are you willing to accept in the light of a no-deal Brexit?”

But Mr Rees-Mogg insisted nobody would die if the UK crashes out of the EU with no agreement – and turned on the neurologist, accusing him of “the worst excess of Project Fear”.

“I’m surprised that a doctor in your position would be fear-mongering in this way on public radio,” he alleged.

When Dr Nicholl replied: “Can I remind you I wrote the plans in mitigation?”, Mr Rees-Mogg lashed out by accusing him of being incompetent.