With just 16 days until Brexit, evidence is emerging of deep tensions in Whitehall as the civil service battles to plan for a no-deal scenario.

Civil servants say they have been frustrated by political paralysis, gripped by inter-departmental rows and shorn of key staff while trying to implement the biggest change to the state’s machinery since the second world war.

Bob Kerslake, a former head of the civil service, said the root of this frustration was the failure of UK politicians to decide on a plan to leave the EU.

“What is making it extremely difficult for civil servants is the paralysis of politicians. They do not know what they are preparing for,” Lord Kerslake said.

“For every task in hand there are at least two streams – the deal and the no deal – and with it a duplication of tasks. What I am getting from them is a desire to serve the government but they cannot do so without instruction and time is running out to prepare properly, one way or the other.

“This is really getting close to mission impossible now.”

As the possibility of a no-deal Brexit has increased, mandarins have spent more time and public money on possible scenarios that may never be needed, with £4bn of taxpayers’ money earmarked for no-deal planning since 2016. They have also been planning for scenarios that would have a major impact on everyday public services.

Kent police has asked for extra help to deal with traffic and related problems if the Channel ports are clogged up, calling for officers to be deployed and placed on standby from around the country. The plan is called Operation Snow Bunting.

Frustrated ministers who are opposed to no deal say the shift in resources should not be happening. One cabinet source said: “I can’t believe we are planning to take officers off the street at a time knife crime is rising.”

There are also plans in place to deploy officers in and around supermarkets and other shops at the end of March. The fear is that people panic-buying food could cause chaos.

Border worries

Civil servants from the Department of Health and the Department for Transport have been helping to coordinate commercial flights to fly radioisotopes, used to detect cancer, into the UK in the event of a no-deal Brexit. At one point officials were considering hiring light aircraft to fly vital blood products to the UK from the European mainland. However, it is understood this plan has been ditched.

“We have asked suppliers to bring in isotopes by air in the event of problems in the Calais-Dover crossing,” a Whitehall source said.

The key focus is the management of the border with France. A source at Highways England, the agency that builds and monitors motorways and major roads, said managers had drawn up plans to relocate 10% of the workforce to Kent in the event of no deal.

The principal worry is not the movement of people, which will be largely unchanged, or even tariffs, which can be levied subsequently, but checks relating to food and animal products where checks are made at or near the border.

Kent council has made plans to park 5,000 lorries on one lane of the M20 and nearby dual carriageways and a further 6,000 at Manston airport to minimise disruption to traffic across the rest of the county.

But Paul Carter, the council’s Conservative leader, says the UK will be reliant on the response of the French, particularly in a no-deal scenario, which he hopes to avoid. “The authorities have promised that Calais will run smoothly and we hope it will, but there were long delays last week when there was a go-slow, when they protested about a lack of resources to handle Brexit,” he said.

Lorries parked on the M20 in Kent. The motorway could be used to park 5,000 lorries in the event of a no-deal Brexit. Photograph: Gareth Fuller/PA

Council planning has focused on the handling of lorries and other freight traffic, which has required a significant effort, with staff working extra time in addition to their day jobs, to reach a position where Carter is confident the plans are in place.

However, at the Channel ports at least, plans are yet to be finalised as to how to handle private cars and tourist traffic wishing to use the crossing. The situation is sufficiently unclear that Carter had hoped May’s deal would pass.

Economic distress

Kent, though, is just part of the story. The Treasury and the Department for Work and Pensions have discussed setting up a hardship fund to deal with the economic fallout of no deal, where the unemployment rate could hit 7%. A total of £1bn has been earmarked. Ministers have been told to expect the suicide rate to rise because of the anticipated greater economic distress.

At least two government agencies have identified the risk of “potential abuse of staff due to customer dissatisfaction” in the event of no deal. A union representative said border agency staff were “rightly concerned” about the possibility that they will be abused by disgruntled passengers at ports and airports.

At first, the creation of the Department for Exiting the EU (DExEU) was seen to be a success in Whitehall, with civil servants eager to work there, and Brexit was considered a path to promotion. But as Theresa May’s negotiations have foundered, there have been growing tensions between DExEU and other departments, and working there has rapidly become less attractive.

Turf wars

Insiders say planning within Whitehall has been complicated by the fact that departments have been taking differing views as to what a no-deal Brexit means. Chris Grayling, the transport secretary, has been more relaxed about planning for no deal, while Michael Gove’s Department for Environment, Food and Rural Affairs (Defra) has been more assiduous.

MPs warned last week that turf wars had emerged between departments fighting for influence and staff, as the centre struggles to hold things together, weakening the UK’s negotiating capabilities.

A report by the European scrutiny committee found power struggles between the Cabinet Office and DExEU meant hundreds of civil servants were working against each other.

It referred to evidence from the former Brexit minister David Davis on the extent to which he had “less influence than expected in drawing up the UK negotiating position and conducting negotiations”.

The paralysis of Brexit has spread to departments that have little to do with the EU. Anger is rising among civil servants in the Department for Education (DfE) and the Ministry of Justice (MoJ) over ministers’ refusal to halt non-essential work while allowing the secondment of hundreds of staff to Brexit-focused departments.

A notice sent to departments two months ago sought 3,500 volunteers to work in Brexit departments such as Defra, the Home Office and HMRC which were floundering under an excessive workload. This was not the first call for staff – but it was the first that warned that supplying departments would still have to pay the wages of the volunteers, leaving senior civil servants unable to hire replacement staff.

Agencies and departments are meant to be reprioritising work or stopping tasks to accommodate this change – but for the most part ministers are not being clear about which policies they are happy to drop. Sources have told the Guardian the DfE and the MoJ have put some policies on hold but have not officially announced which ones. Earlier this week, neither department was happy to say which.

Lack of scrutiny

At Defra, there are concerns over stress-related illnesses among staff, and the department is about to lose its permanent secretary, Clare Moriarty, who is taking over at DExEU after the retirement of Philip Rycroft on 29 March.

The government has about 300 Brexit-related workstreams, but there is almost no scrutiny or discussion about progress, which is unprecedented in Whitehall. Typically, the Infrastructure and Projects Authority releases quarterly or annual progress updates for projects such as the Thames Tideway tunnel or the new Hinkley Point nuclear power station.

“We don’t see any of that for Brexit, although we know it all exists within DExEU. So, the central team know about readiness and risk, but parliament has a limited idea about the levels of readiness across Whitehall,” said Joseph Owen from the Institute for Government.

Official papers released in February said Whitehall was “on track for just over two-thirds of the most critical projects” but then did not say which of the projects were running behind.

A DfE spokesman declined to say which of its policies had been put on hold. “Some people have been moved from a range of areas and they haven’t been replaced, because these are temporary moves. The only projects that have been suspended are those that are not business critical.”

The MoJ also declined to say which policies it has suspended, and instead suggested sending a freedom of information request.

Mike Clancy, the general secretary of the Prospect union, said: “Our members are now spending huge amounts of time preparing for a no-deal Brexit which nobody wants to happen, at the cost of doing the vital day-to-day job of government.

“In the event of no deal, people are going to be angry and it is our members, not ministers, who will have to deal with them.”

Government analysts said the possibility of a no-deal Brexit scenario was unprecedented in terms of Whitehall planning.

“Some businesses were given six years to prepare for auto pensions enrolment,” said Owen from the IfG. “But here government won’t tell businesses what the important tariffs will be yet. No deal requires some political agreements on some big issues, not least what our economic policy will be.”