A classified Powerpoint presentation delivered to ministers warns of food and fuel shortages around Christmas if lorries get stuck at Dover, while 1,500 soldiers are already on standby – ready to hit the streets to help police deal with potential disorder.

The document put together by the Cabinet Office’s EU Transition Task Force also warns of price hikes, power outages, water rationing and animal disease tearing through the countryside due to a shortage of medicines.

Military airdrops may be needed to supply food and medicine the Channel Islands and Royal Navy could be needed to protect British fisherman from illegal EU boat excursions, according to the leaked plans seen by The Sun. Meanwhile Gibraltar could be face a harsh economic blow if it is cut off from Spain after Brexit.

It comes after Brussels’ chief negotiator Michel Barnier said trade talks with London were actually ‘going backwards’, claiming yesterday that there had been ‘no progress whatsoever on the issues that matter’.

His British counterpart David Frost said he believed an ‘agreement is still possible’ but that ‘it is clear that it will not be easy to achieve’. The transition period ends on New Year’s Day next year.

Boris Johnson previously said he didn’t want negotiations to drag on past September so businesses had enough notice to prepare, but Britain has since set a new deadline for October.

Under Government’s plans for an ‘unruly’ departure from the , planners suspect France will enforce ‘mandatory controls on UK goods from day one’.

This could see the flow of deliveries between Dover and Calais drop by 45% over three months, meaning longer queues and a shortage of the 30% of food imported from the bloc, along with medicines, fuel and chemicals used to purify drinking water.

In a worst case scenario this could result in water rationing and power outages in parts of the UK.

Around 75% of medicine imported into Britain passes through Dover and production of animal vaccines has already been stepped down as scientists focus their attention on coronavirus.

Stockpiles of animal medicine could wither if there is no longer a steady flow through Britain’s border – increasing the risk of disease among livestock.

Ministers have been warned that ‘pandemic influenza, severe flooding, a Covid second wave and an unruly exit from the EU transition period could cause a systemic economic crisis with major impact on ­disposable incomes, unemployment, business activity, international trade and market stability.’

These problems could be compounded by ‘coordinated industrial action’, public unrest and a mental health crisis hitting disadvantaged communities the hardest.

A fresh surge of coronavirus hospital admissions could mean the two-metre social distancing rule could be reintroduced, while lockdown measures could carry on ‘well into 2021’, according to the leaked document.

It warns that 5% of local authorities in England are ‘already at high risk of financial failure ­following Covid-19’, meaning some could go bust unless they are bailed out or taken over by Whitehall.

Town halls could face even more of a struggle as inflation drives up the cost of crucial social care services, at a time when ministers have been warned to expect another 24 months of coronavirus cases in care homes.

The Cabinet Office told The Sun its contingency plans include an extra £3billion for the NHS and an extra £600million for social care for the winter.

They said testing capacity will be expanded to 300,000 per day while billions of PPE items are distributed to health and social care staff.

Another £775million has been set aside for new border and customs infrastructure and rules which will be phased in over six months to avoid backlogs.

The Government has promised an advertising campaign to help businesses to make necessary preparations and says finance and data rules will be relaxed to help companies carry on trading with the EU in a no-deal scenario.

Head of the Cabinet Office Michael Gove said: ‘We got Brexit done with a great deal in January.

‘And we are working flat out to make sure the UK is ready for the changes and huge opportunities at the end of the year as we regain our political and economic independence for the first time in almost 50 years.

‘Part of this work includes routine contingency planning for various scenarios that we do not think will happen but we must be ready for, come what may.

‘Whether we trade with the EU on terms similar to Canada or to Australia, a brighter future awaits as we forge our own path.”

A Government spokesperson added: ‘As a responsible government we continue to make extensive preparations for a wide range of scenarios, including the reasonable worst case.

‘This is not a forecast or prediction of what will happen but rather a stretching scenario. It reflects a responsible government ensuring we are ready for all eventualities.’