The European Commission accused countries that want to limit the free movement of people in the European Union of indulging in chauvinism and stereotypes, an apparent reference to Britain's increasingly staunch views on migration.
In a speech to the European Parliament on Wednesday (15 January), Commission President José Manuel Barroso did not refer to Britain or other countries by name, but made his target clear.
British Prime Minister David Cameron has repeatedly called for curbs on free movement and stoked concerns about migrants from Romania and Bulgaria heading to Britain in search of work or social handouts, despite little evidence of it happening.
"Let's not use stereotypes and myths," said Barroso, warning against "narrow, chauvinistic" attitudes and populism as he addressed the European Parliament in Strasbourg.
"Let us not give in to scaremongering and obfuscation."
Britain not alone
Asked about the comments, Cameron's spokesman said Britain was not the only country raising concerns, saying Germany, Austria, the Netherlands and Italy shared Britain's point of view and wanted the issue of free movement and social security addressed.
Worried about rising support for Britain's anti-migration UKIP party ahead of European Parliament elections in May, Cameron wants to cap the number of EU immigrants and stop low-skilled ones relocating unless there is a compelling reason.
His views have caused friction with Nick Clegg, the pro-European deputy prime minister and leader of the Liberal Democrats, who are in coalition with Cameron's Conservatives.
Clegg, a former member of the European Parliament, has said Cameron's ideas risk cutting Britain off from Europe and damaging the economy, which benefited substantially from earlier flows of cheaper labour from Poland.
Britain is working on a report examining the impact of EU migration, but differences between the Conservatives and Liberal Democrats on the issue have delayed its publication.
EU officials have repeatedly criticised Britain for its tough attitude on migration, which has compounded already tense relations between Brussels and London over Britain's desire to renegotiate its 40-year-old relationship with the EU.
British finance minister George Osborne said on Wednesday the legal treaties that dictate how the EU is run were not "fit for purpose" and should be changed, saying he was determined his country would reshape its EU ties.
One of the biggest frustrations among EU officials is Britain's frequent reference to "benefit tourism" and the suggestion migrants from poorer EU member states are moving to the UK to claim unemployment benefits and other social assistance, despite no clear evidence that this is the case.
"Let's have a rational and reasonable debate," Barroso said. If there was any evidence of abuse of free movement rules, he added, countries had an obligation to crack down on it and were at liberty to do so under existing legislation.
The free movement of citizens is one of four "fundamental freedoms" enshrined in EU law, alongside the free movement of goods, services and capital.
It has long been a cherished component of EU membership, allowing students to move easily to any of the 28 member states to study and workers to seek opportunities abroad.
But after years of economic hardship across Europe, far-right, populist or anti-migration parties have made advances in several countries, including Britain, the Netherlands, France and Denmark, pushing migration up the agenda.
It is expected to be a central part of the debate in the run-up to European Parliament elections on May 22-25, with some polls suggesting anti-EU or protest parties on both the right and the left could win up to a quarter of seats.
After Bulgaria and Romania’s EU accession on 1 January 2007, most EU countries lifted the restrictions to their labour markets to workers from these countries.
But restrictions remained in Austria, Belgium, France, Germany, Ireland, Luxembourg, Malta, the Netherlands and the UK.
These countries required Bulgarian and Romanian citizens to have work permits before entering their territory.
According to the Bulgaria and Romania accession treaties, of 1 January 2014 those restrictions are entirely lifted everywhere in the Union.
- Barroso's speech in Parliament (15 Jan. 2014)