Theresa May will not publish the leaked Brexit impact report.

The report will not be released in its current form because it was an "incomplete draft document," a spokesperson for the prime minister said on Tuesday.

The report, produced by the Treasury for the Brexit department, suggests Britain will be worse off outside the EU no matter what scenario.

The PM's spokesperson did not rule out publishing the analysis once it is complete.

LONDON — Prime Minister Theresa May is refusing to release a secret cabinet document detailing the damage Brexit will do to the economy.

The document, which was prepared by civil servants and leaked to Buzzfeed News, shows that Britain would see lower economic growth under every likely Brexit scenario modelled.

A spokesperson for the prime minister today told Business Insider that the report will not be made public because it is "an incomplete draft document" that "had not been signed off" by ministers.

Speaking in the House of Commons, Brexit minister Steve Baker said the government would not release the analysis, because economic forecasts were "always wrong."

May told her Cabinet on Tuesday that the report was "initial work not approved by ministers" which only considered "off the shelf options" for Britain's departure from the European Union, and not the "deep and special partnership" the government seeks to negotiate with the EU, Mays spokesperson said.

"This was a draft document that had not been signed off."

However, they did not rule out the impact analysis being made public once it is completed.

Brexit minister Steve Baker later confirmed that the government would publish the completed form prior to MPs and Lords voting on the final withdrawal deal.

The government will release "appropriate analysis the government has done so the house can make an informed decision," Baker said.

He added that the government cannot be expected to publish the analysis while negotiations with the EU are ongoing because it would risk "harming our negotiation position" and "the national interest."

Baker described the leaked version of the report as "an attempt to undermine our exit from the European Union."

The analysis, commissioned by the Department for Exiting the European Union, looked at the impact of Britain leaving with either a free trade agreement, a Norway-style single market deal, or a no-deal scenario.

Under all three scenarios, Britain would be worse off than if the country decided to remain in the European Union, according to the analysis, which was intended to be presented to May's Cabinet in private over the coming days.

It found that with no deal, UK economic growth would be 8% lower than remaining in the EU and with a free trade agreement it would be 5% lower.

Even under the 'softest' option of remaining inside the European Economic Area but leaving the EU, growth would be 2% lower than staying in.

May under pressure to publish the report

Labour this morning called on the government to publish the findings of the report in full.

Matthew Pennycook, shadow Brexit minister, said: "Labour has made clear since the referendum that Tory Ministers cannot withhold vital information from Parliament and the public about the impact of different Brexit scenarios on jobs and the economy.

"Ministers should publish this information immediately and allow for a full debate in Parliament about its implications."

Conservative MPs Nicky Morgan and Anna Soubry have also joined calls for the report to be released. Nicky Morgan MP. ADRIAN DENNIS : Getty

Morgan, Treasury select committee chair, said: "I think it should be published."

Soubry, who has long been a thorn in the government's side on Brexit from the Conservative backbenches, said: "The people must indeed take back control - at the moment we’re in danger of our future being determined by a small elite of hard Brexit MPs."

Leave-backing MPs have dismissed the report's findings.

Brexiteer and Former Conservative party leader, Iain Duncan Smith, described the leak as "highly suspicious" and said "almost every single forecast coming from government, and most of the international organisations, has been completely wrong."

Smith was echoed by his colleague Jacob Rees-Mogg, who said the report was based on "opinion" rather than "facts."

The parliamentary Brexit committee, led by Labour's Hilary Benn, is likely to discuss the leaked report when it meets on Wednesday, a source close to the committee has told Business Insider.