EVERY part of the UK would suffer an "economic disaster" after Brexit with Scotland forecast to lose at least £15 billion in growth if no Brussels deal is agreed, according to figures leaked from Whitehall’s own analysis.

The numbers show that those areas which backed Brexit in the 2016 referendum would suffer the most.

For example, the north east of England, which overwhelmingly voted to leave, would lose as much as 16 per cent in growth after 15 years if there were no deal with the EU27, while London, which voted to remain, is forecast to lose just 3.5 per cent under the same circumstances.

Last month, the general outlook of the UK Government’s Brexit analysis was leaked.

It predicted after 15 years remaining in the single market would result in UK-wide growth being two per cent lower than current forecasts, securing a trade deal five per cent lower and a no deal eight per cent lower.

Faced with calls to make the full figures public, Theresa May refused, saying it would be “wrong” to publish the analysis as it was merely a draft document, that did not consider the Government’s preferred bespoke deal.

But after Labour threatened a binding Commons vote, which the Conservative Government look set to lose, the Prime Minister relented, indicating she would release the details to MPs and the devolved administrations on a “confidential basis”.

However, Michael Russell, the Scottish Government’s Brexit Minister, threatened to make them public, saying voters had a right to know about the Brexit impact. Downing Street warned Edinburgh against such an action, claiming it would be against the “national interest” to do so and could harm Britain’s negotiating hand.

Yet after MPs were given the detailed figures to read under controlled conditions, they were swiftly leaked and suggest that for Scotland the loss to growth under the three scenarios – single market membership, trade deal or no deal – would be 2.5 per cent, six per cent and nine per cent respectively.

Scotland’s current annual GDP is £164bn. Given the Scottish economy is set to rise over the next decade or so, then the nine per cent predicted loss by 2034 would be at least £15bn.

The Whitehall numbers are similar to those put out by the Scottish Government, which said a no-deal scenario would result in an 8.5 per cent hit for Scotland’s growth after 15 years.

Peter Grant for the SNP said: “The leaked UK Government’s internal Brexit analysis makes for utterly grim reading and Theresa May must now end the shameful secrecy surrounding the UK Government's Brexit plans and publish the papers in full, which we now know will have catastrophic consequences for Scotland and the UK’s economy.”

The Glenrothes MP added: "The leak underlines the case that remaining in the single market and customs union is the only way to minimize that economic harm. It’s time Theresa May stood up to the Brexit hard-liners and started putting jobs and living standards first.”

Willie Rennie, the Scottish Liberal Democrat leader, said: "The Government's own research is now showing that Brexit will be an economic disaster for every part of the UK. We need to stop Brexit before it is too late."

Meanwhile, as the UK’s “war Cabinet” on Brexit met to thrash out a position on Northern Ireland and immigration, Mrs May insisted she would take a “robust” approach to the second phase of Brussels talks.

Her declaration came after the Democrat Unionists’ Ian Paisley urged the UK Government to take a “no surrender” approach to Brussels in the wake of a leaked EU27 position paper, which suggested the bloc could impose sanctions on the UK during the transition phase, including limiting access to the single market, if it did not abide by European law during the two-year period.

Mrs May told MPs during PMQs: "What matters is the positions we take in the negotiations as we sit down and negotiate the best deal. We've shown we can do that. We did it in December and we are going to do it again."