EU officials are working on the basis that the UK economy will be hit up to 10 times harder by a no-deal Brexit than the continent's, the latest analysis by the European Commission shows.

The working assumption in Brussels is bad news for Tory leadership contenders like Boris Johnson, who are hoping to use the threat of a no-deal Brexit as part of their strategy for renegotiating Theresa May’s Brexit deal.

But with the EU convinced that the UK will fare much worse than the continent if it decides to crash out, the brinkmanship may struggle to produce results.

A “state of play” document put out by the commission this week, meant to brief EU leaders, MEPs, and central bankers on the current situation, cites a 2019 estimate by the IMF that the long-term effect on the EU’s GDP by a no deal will be “well below 1 per cent”. The commission says this is “in line with most other studies”.

By contrast, when looking at how the UK fares, the commission cites figures ranging from 3 per cent to 8 per cent for the hit to the UK economy, including the British government’s own 2018 estimate of 7.7 per cent.

Tariffs in the event of a no-deal Brexit Show all 15 1 /15 Tariffs in the event of a no-deal Brexit Tariffs in the event of a no-deal Brexit Pork There will be tariffs on pork in order to protect British farmers Getty Tariffs in the event of a no-deal Brexit Cheese There will be tariffs in place on some cheeses including €22.10/100kg of cheddar, €19.10/100kg of processed cheese and €18.60/100kg on some blue cheeses Getty Tariffs in the event of a no-deal Brexit Milk There will be no tariffs in place on milk Getty Tariffs in the event of a no-deal Brexit Car Parts There will be no tariffs on car parts imported from Europe PA Tariffs in the event of a no-deal Brexit Cars However finished cars will face tariffs of 10.6% Getty Tariffs in the event of a no-deal Brexit Alcoholic drinks There will be no tariffs on alcoholic drinks - except on some rums due to ingredients used in their distilling process Getty Tariffs in the event of a no-deal Brexit Beef There will be tariffs on beef in order to protect British farmers Getty Tariffs in the event of a no-deal Brexit Fish There will be no tariffs on many types of fish including cod, haddock, salmon and sea bass Getty Tariffs in the event of a no-deal Brexit Fruit and vegetables There will be no tariffs on almost all fruit and vegetables Getty Tariffs in the event of a no-deal Brexit Chocolate There will be no tariffs on chocolate or other cocoa products Getty Tariffs in the event of a no-deal Brexit Poultry There will be tariffs on poultry in order to protect British farmers Getty Tariffs in the event of a no-deal Brexit Ceramics There will be some tariffs in place on ceramis Getty Tariffs in the event of a no-deal Brexit Steel There will be no tariffs on steel Getty Tariffs in the event of a no-deal Brexit Coal There will be no tariffs on coal Getty Tariffs in the event of a no-deal Brexit Lamb/Mutton There will be tariffs on the meat of sheep in order to protect British farmers Getty

“As the commission has constantly stressed, contingency measures can only mitigate the most significant disruptions of a withdrawal without an agreement. While the commission does not speculate on the possible economic implications of different scenarios, it is clear that a withdrawal of the United Kingdom without an agreement would have a serious negative economic impact, and that this impact would be proportionally much greater in the United Kingdom than the EU27 member states,” the document says.

“Preparations by member states and stakeholders are likely to reduce their individual exposure to the negative impact of a withdrawal without an agreement. A high level of preparedness across all sectors of the economy will also mitigate the negative impact.”

The economic assumptions are based on the British economy being subject to WTO “most favoured nation” tariffs, which apply to WTO members in the absence of other agreements. Under the withdrawal agreement struck by the UK, a multi-year transition period would apply, during which the UK continued to benefit from EU policies, while a replacement deal was negotiated.

The judgment comes just days after a leaked UK cabinet paper warned that the UK was not ready for a no-deal Brexit on 31 October, when the current extension of the Article 50 period will expire if it is not extended again.

The note, obtained by the Financial Times, said it would take “six to eight months” to build up supplies of medicines for a no deal, and that it would take “at least 4-5 months” to make traders ready for new border checks that might be required.