LONDON - Britain will face shortages of fuel, food and medicine if it leaves the European Union without a transition deal, jamming ports and requiring a hard border in Ireland, official government documents leaked to the Sunday Times show.

The Times said the forecasts compiled by the Cabinet Office set out the most likely aftershocks of a no-deal Brexit rather than the worst case scenarios. Prime Minister Boris Johnson's office said it did not comment on leaked documents.

The newspaper said up to 85% of lorries using the main channel crossings "may not be ready" for French customs, meaning disruption at ports would potentially last up to three months before the flow of traffic improves.

The government also believes a hard border between the British province of Northern Ireland and the Republic of Ireland, an EU member, will be likely as current plans to avoid widespread checks will prove unsustainable, the Times said.

"Compiled this month by the Cabinet Office under the codename Operation Yellowhammer, the dossier offers a rare glimpse into the covert planning being carried out by the government to avert a catastrophic collapse in the nation's infrastructure," the Times reported.

"The file, marked "official-sensitive" - requiring security clearance on a "need to know" basis - is remarkable because it gives the most comprehensive assessment of the UK’s readiness for a no-deal Brexit."

Asked about the Yellowhammer documents, energy minister Kwasi Kwarteng told Sky News: "I think there's a lot of scaremongering around, and a lot of people are playing into 'Project Fear' ... We've got to prepare for no deal."

"We will be fully prepared to leave without a deal on the 31st of October."

The United Kingdom is heading towards a constitutional crisis at home and a showdown with the EU as Johnson has repeatedly vowed to leave the bloc on Oct. 31 without a deal unless it agrees to renegotiate the Brexit divorce.

After more than three years of Brexit dominating EU affairs, the bloc has repeatedly refused to reopen the Withdrawal Agreement which includes an Irish border insurance policy that Johnson's predecessor, Theresa May, agreed in November.

Brexit minister Stephen Barclay said on Twitter he had signed a piece of legislation which set in stone the repeal of the 1972 European Communities act - the laws which made Britain a member of the organization now known as the EU.

Though his move was largely procedural, in line with previously approved laws, Barclay said in a statement: "This is a clear signal to the people of this country that there is no turning back (from Brexit)." -Reuters