The spokesman of UK Prime Minister Theresa May has stated that the leaked partial document on Brexit's impact on the UK economy is part of a range of analysis across the government on the country's withdrawal from the European Union.
"The PM said this was initial work, not approved by ministers, which only considers off-the-shelf scenarios. No analysis was made of the bespoke arrangement we seek as a matter of government policy," the spokesman told reporters.
Titled "EU Exit Analysis — Cross Whitehall Briefing", the report claims that irrespective of the deal clinched between London and Brussels, UK's economic growth will slow down outside the European Union.
The growth is expected to be eight percent lower in the next fifteen years if Britain withdraws from the EU with signing a deal, and five percent less if the UK negotiated a free trade agreement, according to the report.
Even under the soft Brexit scenario which stipulates the UK remaining in the single market, the country's economy will shrink by two percent within the same period, the document suggests.
The BBC cited a source as saying this "early draft of analysis" looks into "different off-the-shelf arrangements that currently exist as well as other external estimates."
At the same time, the source said that the report includes "a significant number of caveats and is hugely dependent on a wide range of assumptions."
The survey comes amid the increasing pressure on UK Prime Minister Theresa May, with some senior Tory members demanding on her resignation.
International Trade Secretary Liam Fox, for his part, urged them to "live with disappointment" and agree on a soft Brexit scenario.
The Brexit talks between the United Kingdom and the European Union, which started in June 2016, are due to wrap up by the end of March 2019. In December 2017, the sides completed the first phase of the negotiations, which included a discussion on the issue of citizens' rights.
The second phase includes the talks on the transition period in EU-UK relations after Brexit, and their future long-term trade and security cooperation.