A no-deal Brexit would threaten Britain’s food supply with a "catastrophe" as deliveries would be disrupted and prices hiked in the shops.

The stark warning from Gordon Brown comes on the eve of what promises to be a momentous parliamentary clash at Westminster over its role in Brexit with the backdrop of street protests and challenges in the courts to stop a no-deal outcome.

As the UK Government launched its biggest ever public information campaign, Get Ready for Brexit, at an estimated cost to taxpayers of £100 million, Michael Gove, the Cabinet Office Minister, was accused of having “sold his soul to the devil” after he refused to say whether the UK Government would accept a parliamentary vote to block a no-deal Brexit.

Mr Brown is supporting a call from the GMB, the trade union for food workers and campaign group Hope Not Hate contained in a letter to Boris Johnson, demanding he come clean on the potentially disastrous risks a no-deal Brexit would pose to the UK’s food supply.

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The former Prime Minister said: “A no-deal Brexit threatens the UK’s food supply chain. Imports of almost a third of our food could be subject to disruption.

“Uncertainty, restricted supplies and a weakened pound could raise prices. This would be a catastrophe for the food industry but also for family budgets, hospitals and those driven to food banks due to the decimation of our social security system over the last decade.”

However, Mr Gove took to the airwaves with a message of reassurance and suggested Britain’s food supply would be largely unaffected by a no-deal Brexit.

Asked on the BBC’s Andrew Marr Show whether there would be shortages of fresh food with a no-deal, the Cabinet Office Minister said: "Everyone will have the food they need,” stressing: “No, there will be no shortages of fresh food.”

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The Scot added: “Some prices may go up; other prices will come down."

But the trade body for UK retailers insisted it was "categorically untrue" that fresh food supplies would be unaffected with a no-deal outcome.

A spokesman for the British Retail Consortium pointed out the Government's own assessments had shown the flow of goods through the channel crossings could be reduced by up to 60 per cent from day one, as would the availability and choice of some foods.

“The reality remains a no-deal Brexit in October would present the worst of all worlds for our high streets and those who shop there.

"Retailers will be preparing for Christmas, stretching already limited warehousing capacity and the UK will be importing the majority of its fresh food from the EU, magnifying the impact of border delays," he added,

The warning came as a leading doctors’ union claimed in a briefing paper published today that a no-deal Brexit would have a devastating impact on the NHS as services prepared for the onslaught of winter pressures.

Dr Chaand Nagpaul, Council Chairman of the British Medical Association, said: "Cancelled operations, missed cancer treatment targets and patients in corridors waiting for hours on end to be seen; recent winters have seen unprecedented scenes unfold in our hospitals, GP surgeries and across the NHS, with patients suffering and staff under increasing pressure as resources and capacity struggle to keep up with rocketing demand.

"Add to that chaos a no-deal Brexit and the disintegration of the health service becomes an ever more real prospect."

At Westminster, battle lines are being drawn on both sides of the divide between Parliament and Government.

Tory whips and Whitehall officials were last night expected to meet at the PM’s country retreat of Chequers for a strategy meeting while opposition leading figures were said to be in “ongoing discussions” as they plan their own parliamentary tactics.

Ahead of an emergency meeting of the Shadow Cabinet on Monday, Jeremy Corbyn will say in a speech that Labour is doing "everything necessary to pull our country back from brink".

Declaring that the Johnson Government’s “attack on democracy will be resisted,” the Labour leader will say: “The people will not allow a phoney populist cabal in Downing St, in hock to the vested interests of the richest, to deny them their democratic voice.”

Ian Blackford for the SNP called for unity, saying: “It’s time for politicians to put their constituents before their own political ambitions and tell Boris Johnson that no-deal is not an option.”

Opposition forces are set to strike tomorrow when Parliament returns, seeking an SO24 emergency debate. Rebel MPs are hoping John Bercow, the Commons Speaker, will defy convention and allow this to end with a vote to ensure they can take control of the Commons Order Paper on Wednesday.

Time is of the essence as pro-Government peers could seek to filibuster day and night on the rebel MPs’ bill seeking a delay to Brexit. But one senior opposition source said there were ways to get round a Lords’ “mattress strategy”; one option being a move to make Parliament sit over a weekend. “We can do it if need be,” insisted the source.

Meanwhile, Mr Gove came under sustained fire after refusing to say the Government would accept a parliamentary vote that blocked a no-deal outcome.

He told the Marr Show: “Let's see what the legislation says. You're asking me about a pig in a poke. And I will wait to see what legislation the Opposition may try to bring forward."

But Sir Keir Starmer, the Shadow Brexit Secretary, described Mr Gove’s comments as “breath-taking,” while his Labour colleague, Jon Trickett, the Shadow Cabinet Office Minister, said: "Boris Johnson has shown his contempt for our democracy and the British people. Any move to ignore an act of Parliament would be a full-blown attack on our constitution.”

Tom Brake for the Liberal Democrats said: “We are in real threat of our democracy being silenced. This authoritarian power-grab must be stopped.

"From shutting down Parliament to ignoring expert warnings today from the British Retail Consortium on the danger of food shortages, it appears Michael Gove has sold his soul to the devil.”