Britain would 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, according to government documents leaked to The Sunday Times of London, a scenario Brexit opponents have long warned about.

The forecasts compiled by the Cabinet Office set out the most likely aftershocks of a no-deal Brexit rather than the worst-case scenarios, the newspaper said.

Up to 85 percent of trucks 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 documents suggest, according to the British news outlet.

The files show that the government also believed that a hard border between Northern Ireland, which is part of Britain, and Ireland, which will remain a European Union member state, would be most likely since current plans to avoid widespread checks would prove unsustainable, the report said.