A no-deal Brexit could cause “severe disruption” to the British economy and put jobs and livelihoods at risk, MPs have warned in a strongly worded report.

The House of Commons Exiting the European Union Committee heard evidence from the pharmaceutical industry that a no-deal Brexit would be a “leap into the unknown”, potentially putting patient safety at risk and increasing costs for the NHS.

The MPs also said there was no reason to doubt concerns there could be “interruptions to food supplies in respect of certain products” because of the “disastrous” impact on UK farming.

They warned that tariffs adding €3,000 to the cost of British-made cars in European Union markets would but the sector at a “competitive disadvantage”.

The report — which was opposed by four Tory Brexiteer members of the committee - also cast doubt on Conservative leadership hopeful Boris Johnson’s claim that the UK and EU would be able to maintain existing rules while they negotiate a free-trade deal.

Mr Johnson has argued that a provision under the General Agreement on Tariffs and Trade — known as Gatt 24 — could be used to avoid tariffs under World Trade Organisation (WTO) rules for up to 10 years.

But the committee said: “It requires an agreement between the two parties, a plan as to how the end state will be reached, and for this agreement to notified to all parties to the WTO. By definition leaving without a deal means there is no agreement.”

Gatt 24 therefore “does not provide a means to mitigate the risks to EU-UK trade in the event of a no-deal exit”.

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The MPs who opposed the report were European Research Group chairman Jacob Rees-Mogg, a prominent supporter of Mr Johnson; Peter Bone; Andrea Jenkyns and Sir Christopher Chope.

Mr Johnson has built his Tory leadership campaign around a “do-or-die” commitment to leave the EU on October 31st, with or without a deal.

The committee’s chairman, Labour MP Hilary Benn, said: “A no-deal Brexit, with no Gatt 24 agreement, would be at best a foolhardy gamble and at worst, lead to severe disruption, and it is neither desirable nor sustainable as an end state for our economic relations with the EU.

“This clear evidence reinforces our previous conclusion that a ‘managed no deal’ cannot constitute the policy of any responsible government.”

The committee dismissed the argument used by Brexiteers that a no-deal departure would force the EU to come back to the table because of the need of the 27 remaining members to trade with the UK.

“This is, at best, a gamble,” the MPs said. “At worst, it could lead to severe disruption of the economy, pose a fundamental risk to the competitiveness of key sectors of the UK economy and put many jobs and livelihoods at risk.”

The committee’s report follows a warning from the Office for Budget Responsibility that a no-deal Brexit could push the UK’s economy into recession and increase borrowing b£30 billion a year.

A Department for Exiting the EU spokesman said: “We’ve been preparing for nearly three years to minimise disruption in the event of no deal, and we have over 300 work streams looking at specific no-deal plans across a range of sectors which are well advanced, with departments making sensible decisions about prioritisation.

“We continue to provide people and businesses with the information they need to prepare, and encourage them to take action to avoid disruption.”

The committee’s report said:

- A no-deal Brexit would mean “creating circumstances that incentivise the UK services industry to relocate” parts of its operations to the EU

- Leaving without a deal would “create considerable bureaucratic and legal obstacles” for businesses that depend on free movement of data between the UK and EU

- The UK’s position as a leading destination for venture capital investment in technology firms will be jeopardised without a deal with Brussels

- Sheep meat exported to its main EU market would face tariffs approaching 50 per cent “bringing the viability of that sector into question”

- PA