David Cameron has a "duty to publish" an official report that fails to back up the government's case for tightening restrictions on EU migrants, the former chief economist at the Cabinet Office has said.
Jonathan Portes, who now runs the National Institute of Economic and Social Research, told the Huffington Post UK: "It's not surprising that the government's review of the evidence should have concluded that EU migration is broadly good for the UK economy; and that it should have failed to provide any hard evidence that 'benefit tourism' is a problem. That is what the research shows.
"What I would say is that having taken the trouble to commission a comprehensive review of the evidence on this topic, which is clearly one of great public interest, the government has a duty to publish it in a timely fashion."
The Conservatives' Lib Dem coalition partners have been less keen on recent proposals to restrict eastern European migrants' access to benefits and have stressed the virtues of free movement inside the EU.
Liberal Democrat MEP Sarah Ludford told HuffPost UK: “I’m disappointed that Conservative ministers are blocking publication of a report which would help inform the public debate about EU migration ahead of the crucial European elections in May.
"They presumably recognise that the truth does not match the myth they and UKIP have created about EU ‘benefit tourism’. In fact European migrants contribute a third more in taxes than they receive in benefits in this country and are less likely to claim benefits than British people.
Ludford added: "It's a great pity that an exercise – the 'EU Balance of Competences review' – meant to be an objective analysis is being subverted for party political ends."
Labour hit out at the government's refusal to publish the report, with MEP Mary Honeyball telling HuffPostUK: "Theresa May's failure to find meaningful evidence to back up the government's position illustrates the Emperor's New Clothes nature of the Eurosceptic argument.
"By all means the Tories can discuss European freedom of movement - but they must do so in a scientific way, rather than using political gestures and grandiose rhetoric to distort the debate."
Others, like Atul Hatwal, director of the cross-party pro-immigration pressure group Migration Matters, told HuffPostUK: "If the Home Office report is indeed finished we call on the government to publish it as planned, complete with the submissions from business leaders and academic experts that have been used as the basis for its findings."
The clamour over the government's secret report on EU migration comes after the Financial Times revealed that the prime minister had delayed the Home Office's report into the issue until after the European Parliament elections in May.
Labour's shadow minister for immigration, David Hanson MP, said: “We need a calm, rational and evidenced based debate on immigration so it’s worrying that it appears David Cameron is hiding facts that don’t back up this Government’s empty Rhetoric on immigration; the Prime Minister needs to publish the report now."
One official quoted by the FT said: “They can’t bring themselves to publish the report before the European elections because they would have to admit that freedom of movement is a good thing.”
On Monday, Robert Chote, head of the government's independent forecaster, the Office for Budget Responsibility, piled on the pressure when he warned MPs that government plans to cut net immigration to below 100,000 per year could push up Britain's debt to around 120% of GDP by 2062.
Speaking to the Treasury select committee, he said: “There will be fewer net inward migrants, making the fiscal position somewhat worse."