London - Prime Minister Theresa May's government has sought to play down its own leaked analysis suggesting Britain would be worse off whatever deal it strikes with the EU, warning it was made public to undermine Brexit.
May assured ministers at their weekly cabinet meeting that the report leaked Monday was only preliminary and did not take into account the government's preferred option of a trade deal with the European Union.
In parliament on Tuesday, Brexit minister Steve Baker said the leaked report was a "selective interpretation of a preliminary analysis. It is an attempt to undermine our exit from the European Union".
The economic impact assessment, dated last month and seen by BuzzFeed News, showed growth would be weaker under three of the most plausible Brexit scenarios.
It found that if Britain remained in the EU's single market through membership of the European Economic Area, growth would be two percent lower over the next 15 years compared with current forecasts.
Under a comprehensive free trade agreement with the EU, growth would be five percent lower than expected.
If Britain fails to strike any new trade deal and reverts to World Trade Organization rules, growth would be eight percent lower than forecast.
The report was leaked at a highly sensitive time, as May comes under pressure from eurosceptics in her Conservative party to change her strategy ahead of the start of formal trade talks with the EU in April.
Eurosceptics fear the government is moving towards retaining close ties with the EU, which might limit any economic damage but which they argue would be "Brexit in name only".
Conservative MP Iain Duncan Smith said the timing of the leaked report was "highly suspicious" and noted that long-term forecasts were often wrong.
Jacob Rees-Mogg, chairman of the European Research Group of eurosceptic Conservative MPs, said the findings were "highly speculative".
But pro-European opposition Labour MP Chris Leslie said it explained why ministers have refused to publish any detailed Brexit analysis so far.
"The government must now publish their analysis in full, so that MPs and the public can see for themselves the impact that Brexit will have and judge for themselves whether it is the right thing for our country," he said.
But Baker said: "Ministers have a duty not to publish anything that could risk exposing our negotiating position."