With only days to go until Brexit and no sign of progress in breaking the deadlock, Whitehall officials are poised to activate emergency no-deal plans.

Theresa May has appealed to the EU for a short delay to Brexit up to 30 June after MPs twice rejected her deal and ordered her to extend the two-year Article 50 process.

But European Council president Donald Tusk turned up the pressure, saying Brussels would permit a short delay but only if MPs back May’s deal.

While the prime minister holds talks in Brussels, attentions at home are fixed on mitigating potential chaos from a disorderly Brexit, as part of high-level plans codenamed Operation Yellowhammer.

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Security

Operation Yellowhammer has been described as the “biggest peacetime project in the history of the civil service”, with much of the attention focused on border security and policing.

The Home Office has announced an additional £3.5m for Kent Police to managed the “unique demands” Brexit posed to the county, due to its proximity to continental Europe. It takes the total funding for Kent to £4.3m.

Defence secretary Gavin Williamson promised MPs that 3,500 troops would be on standby, in case extra personnel were needed at British ports, at the border or to help police if there is civil disobedience.

Transport

The government warned that air travel would be hit by a no-deal Brexit, as UK and EU licensed airlines would lose the automatic right to operate air services without seeking advance permission.

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It says it would “envisage granting permission to EU airlines to continue to operate”. Up to 5 million flights are at risk if the UK leaves the EU without a deal, according to the International Air Transport Association (IATA).

On the roads, officials are grappling with methods to cope with thousands of lorries that pass through Dover and the Channel ports, which could require border checks under a no-deal exit.

Transport secretary Chris Grayling was much mocked when dozens of lorries occupied a disused airfield in Kent in a live test of plans to ease congestion on roads if Britain leaves the bloc without a deal.

The Department for Transport (DfT) confirmed that 89 vehicles are involved in the exercise with each being paid £550 – amounting to £48,950.

Medicines

Ensuring medical supplies can pass freely has been a priority for the government, with ministers ordering pharmaceutical firms to build “buffer stocks” of key items to avoid disruption.

Health secretary Matthew Hancock bragged that he was the largest buyer of fridges in the world as the NHS boosts its capacity to store vital drugs.

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Ministers also tried to secure additional freight capacity to ship medical goods to the UK – but plans were mired in controversy after Grayling awarded contracts to a firm that had no ships.

Food

Industry experts have consistently warned that if Britain leaves the EU without a deal then there will be an increase in food prices and a shortage of fresh produce.

Under the government’s no-deal plans, tariffs will be scrapped or slashed on almost all imports after a no-deal Brexit, raising the prospect of job losses in UK firms.