Prime Minister David Cameron on Wednesday called on campaigners for Britain to leave the European Union to give detailed projections of the expected economic impact.
"A government document will today show the alternatives to EU membership would damage Britain," Cameron said on Twitter.
"Leave campaigners must now set out what their detailed plan for Britain outside the EU is - and its impact on the economy and prices," he said.
The government analysis will say that Britain would be "weaker, less safe and worse off" outside the EU, according to media reports, echoing similar arguments by Cameron.
Voters in a June 23 referendum are expected to be asked the singlequestion: Should the United Kingdom remain a member of the EuropeanUnion or leave the European Union?
In the debate over a British exit, or Brexit, Cameron has urged people to vote for remaining part of the EU after he negotiated a deal for reforms that would give Britain a "special status."
A YouGov poll for The Times last week suggested that 38 per cent of people want to leave the EU and 37 per cent want to remain, with the other 25 per cent undecided or not planning to vote.