Mr Brown said the publication yesterday of the government's Operation Yellowhammer report - which shows the potential impact of the UK leaving the EU without a deal - was proof there would be a sharp rise in food and fuel prices which would "wreak havoc with family budgets".
As a result, he said, he has now written to the Prime Minister about the risk vulnerable people, to medical supplies and the precarious position of food banks
Speaking at a rally in Edinburgh this evening, Mr Brown also revealed that more than 2,000 faith leaders have signed a letter to Mr Johnson, warning of the risk to the vulnerable. He said SUSTAIN, an alliance of charities related to food and farming, has also called for a hardship fund to compensate for rising food and fuel prices.
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.”
According to the former Prime Minister, more than one million medical consignments come in from Europe every day, and said while plans to "stockpile and to fly medicines in and to issue a ‘significant shortages protocol’," the disruption at Dover, predicted by the Yellowhammer document, would affect 75 per cent of all UK medical supplies.
He said medication such as insulin, Epi-pens and radioisotopes for cancer treatment would all be seriously affected. “While on flu vaccines, we already rely on five million doses imported every year, mainly from Europe.
“But with a new more lethal flu strain discovered recently in Australia and flu vaccines being reconfigured to meet a new challenge, we now know that because of the new version at least one million doses cannot be ready in sufficient time to be imported before October 31st and now may not come in quickly enough after that date."
On food supplies, Mr Brown said that prices would rise by 10 per cent "if the flow of trucks through the main UK ports, notably Dover, drop - as forecast in the reasonable worst case scenario – and this level of disruption continued for weeks - something unprecedented in peacetime Britain.
“Frankly, it is a disgrace that Britain depends on food banks and it is a tragedy that we are now seeing food banks forced to the wall just to afford to buy the food that people need.
“And with British energy supply relying on the energy inter-connector with mainland Europe, gas and electricity prices, which rose between 16-18 per cent after the 2016 referendum as the pound devalued, could rise again - a factor the government has had to recognise in Yellowhammer but which would hit poorest households most.”
He said the Yellowhammer documents demonstrated the need for Brexit to be put back to the public for a final say.
Mr Brown's comments were supported by Ian Murray, Labour MP for Edinburgh South, who said: "The government’s own Yellowhammer document shows how devastating a no-deal Brexit will be. Boris Johnson is determined to deliver that, so we must do all we can to prevent a no-deal and get any deal parliament agrees back to the people for a final say referendum.”
Nick Lowles, chief executive of HOPE not hate, added: “A no-deal Brexit risks harming all sectors of the economy from food to industry and services.
“The effects on people’s wages, living standards and employment prospects would create the type of social pressures that the far-right are waiting to exploit. We mustn’t let a shock no-deal Brexit damage the social unity that our communities have worked together to build.”