Using distinctly undiplomatic language, the commissioner, who has refused to contemplate any tightening of EU rules before Romania and Bulgaria have free movement rights next month, made an astonishing attack on Britain’s welfare system.

“It seems that some national systems are too generous. Don’t blame the commission or EU rules for national choices and national regulatory systems,” she said.

“If member states want to restrict the availability of social benefits to EU citizens they can do two things: First, change their national systems to make them less generous. Second, apply the existing EU rules which provide safeguards to counter abuse, fraud and error: for example possible expulsion orders and re-entry bans in case of abuses.”