Britain will face shortages of food, fuel and medicine if it leaves the EU without a deal.
That's according to leaked government documents published by the UK's Sunday Times.
Jammed ports and a hard border in Ireland are also forecast in the dossier, which was reportedly compiled this month by the UK's Cabinet Office under the codename "Operation Yellowhammer".
The British newspaper said the documents set out the most likely aftershocks of a no-deal Brexit - rather than the worst-case scenarios.
Something the British government denies.
Writing on Twitter, Cabinet Minister Michael Gove, who's in charge of coordinating preparations for leaving the EU without a deal,
Said the documents do show a worst-case scenario and that very significant steps have been taken in recent weeks to accelerate Brexit planning.
The Sunday Times said up to 85% of lorries using the main channel crossings "may not be ready" for French customs. That means disruption at ports would potentially last up to three months before the flow of traffic improves.
Avoiding a hard border between EU member Ireland and Northern Ireland has long been one of the most hotly contested elements of the Brexit divorce bill.
The leaked documents reportedly show the government believes a hard border will be likely.
Britain is heading towards a constitutional crisis at home and a showdown with the EU.
This week Prime Minister Boris Johnson will meet with French President Emmanuel Macron and German Chancellor Angela Merkel to tell them that Westminster parliament cannot stop Brexit
And a new deal must be agreed if Britain is to avoid leaving the EU without one.