Sky reported that the slide was prepared in the final weeks of Theresa May’s tenure as prime minister.
PA understands the document was shown to ministers but not signed off by the government, meaning it was not official policy.
But the worst case scenarios – broken down into first day, first fortnight and first month categories – also included potential friction at sea between UK and EU fishing vessels.
Within 24 hours, it says cross-border agriculture trade in Northern Ireland “virtually stops” as other trade “slows”.
In the first fortnight column, it details: “Potential consumer panic and food shortages, even in areas which are not directly affected at the border.”
And it warns of a “possible increased risk of serious organised crime including people smuggling and illegal migration”.
The first month could also see heightened policing resources becoming “unsustainable”, as operational gaps in security “continue to emerge”.
A No 10 spokeswoman said: “We do not comment on leaked documents.”
The Prime Minister was on Thursday to chair his first meeting of the Brexit war cabinet – comprising of the Chancellor, Foreign Secretary Dominic Raab, Chancellor of the Duchy of Lancaster Michael Gove, Brexit Secretary Steve Barclay and Attorney General Geoffrey Cox.
On the same day, the Bank slashed its growth forecast to 1.3% for both this year and next, down from the 1.5% and the 1.6% previously predicted.