Civil servants are reportedly preparing contingency plans for the possibility that Britain is left without food, fuel and medicines after crashing out of the EU without a deal.
Whitehall officials are said to have been planning models for mild, severe and “Armageddon” outcomes to a no-deal exit next year.
The Sunday Times says planning to deal with the port of Dover collapsing “on day one” is underway, with fears that the UK could face a shortage of crucial supplies within a fortnight.
A source told the paper the outcome would mean officials would have to charter aircraft, or use the military to transport supplies to the furthest corners of the country.
“In the second scenario, not even the worst, the port of Dover will collapse on day one,” they said.
“The supermarkets in Cornwall and Scotland will run out of food within a couple of days, and hospitals will run out of medicines within two weeks.”
They added: “You would have to medevac medicine into Britain, and at the end of week two we would be running out of petrol as well.”
It is understood that the plans were drawn up last month ahead of the weekly Inter-Ministerial Group on Preparedness, but that they have been “locked in a safe” and only shared with a select few ministers.
A spokesman for the Brexit department confirmed to the paper that the discussions had taken place, but that it was “completely false” that worst scenario would unfold.
“A significant amount of work and decision-making has gone into our no-deal plans, especially where it relates to ports, and we know that none of this would come to pass,” they said.
A senior official added however that ministers feared the EU would not necessarily reciprocate were Britain to open its borders in an attempt to keep goods flowing following a no deal scenario.
“We are entirely dependent on Europe reciprocating our posture that we will do nothing to impede the flow of goods into the UK.
“If, for whatever reason, Europe decides to slow that supply down, then we’re screwed.”
Elsewhere the paper says one official warned the EU summit later this month could end up as a “car crash” because “no progress has been made since March” in reaching a long term deal.
They add that Theresa May and David Davis last week clashed over the release date of the planned Brexit white paper, while the 150-page document itself still contained “large areas of red ink” where ministers were yet to reach agreement.