The Government is “still not telling the truth” about medicine and food shortages that would result in the event of a no-deal Brexit, Gordon Brown has said.

The former prime minister argued that the Operation Yellowhammer report looking at no-deal scenarios concealed the full truth about shortages to vital medicines and drugs.

Ahead of a speech in Edinburgh, Mr Brown revealed he had written to the Prime Minister accusing him of “dishonest claims” that underestimate the risks posed if the UK leaves the EU without a deal.

European Parliament election
Former prime minister Gordon Brown (Andrew Milligan/PA)

Mr Brown said: “The truth is that we are not taking back control but losing control – of medical supplies and food and energy prices.

“The worst-case scenario document downplays the risks to medical supplies, the threat to household budgets and the damage inflicted on the most vulnerable.

“We now know from Yellowhammer that no-deal Brexit is an unnecessary act of self-harm but ministers are still not telling the truth about the sheer scale of the self-inflicted wounds.”

In his speech, the former Labour leader is expected to go into detail about the various risks to medical supplies, as well as claiming that sharp food and fuel price rises will “wreak havoc” with family budgets and hit the poorest hardest.

The Operation Yellowhammer report was finally released on Wednesday night after the UK Government was defeated in the House of Commons and forced to release the document, albeit a heavily redacted version.

The six-page document, dated August 2, warns of disruption at channel crossings for at least three months, an increased risk of public disorder and riots on the streets, and some shortages of fresh food.

Describing the situation as “unprecedented”, Mr Brown will add: “Given the information we now have, the Prime Minister must do far more than meet his guarantee that medical supplies will be available for everyone for life-saving treatments.

“Nor can he guarantee that our food supplies – 30% of which come from mainland Europe – can come in uninterrupted without, as the Cabinet Secretary fears, pushing food prices up by 10%.”

Michael Gove, the Cabinet minister with responsibility for no-deal planning, said the Government had taken “considerable steps” to prepare for a safe departure if Mr Johnson failed to get a deal and took the UK out of the EU.

On Wednesday, he said the Government would be publishing “revised assumptions … in due course alongside a document outlining the mitigations the Government has put in place and intends to put in place”.