European Commission President Jose Manuel Barroso has accused those seeking new limits to migration between EU member states of "chauvinism" and "scaremongering".
Mr Barroso did not mention any countries by name, but his comments are likely to be seen as a rebuke to the UK after Prime Minister David Cameron's repeated warnings about migrants from eastern Europe coming to Britain to claim welfare.
Speaking to the European Parliament in Strasbourg, Mr Barroso issued a strong defence of free movement for EU workers, and warned the issue was "in danger of being subject to all kinds of populist rhetoric rather than objective assessment".
Mr Barroso appealed: "Let us work together in a constructive and objective fashion. Let's not use stereotypes and myths. Let's have a rational and reasonable debate. Let us not give in to scaremongering and obfuscation."