PRESS ASSOCIATION -- A UK "right to reside" test on EU nationals based in the country is a breach of EU law, the European Commission has warned.
Brussels threatened it will take legal action unless the test - which determines who qualifies for specific social security benefits - is dropped.
A Commission statement said the Government has two months to advise Brussels what it is doing to bring domestic social security rules in line with EU requirements.
"Otherwise, the Commission may decide to refer the UK to the EU's Court of Justice," said a statement.
Conservative MEP Julie Girling slammed the move as an interference by "unelected bureaucrats" in UK domestic policy.
Ms Girling, the Tory spokesman on employment and social affairs in the European Parliament, went on: "British taxpayers will want to know why their hard-earned money should now be directed straight into the pockets of any EU national who chooses to come here and make a claim.
"This can only lead to a boom in benefits tourism. And with our generous system, Britain will be destination of choice."
Under UK rules a range of benefits - child benefit, child tax credit, state pension credit, jobseekers' allowance and unemployment support allowance - are only given to those with a "right to reside".
That is automatic for UK nationals, but residents from other EU countries have to pass a "right to reside" test.
This, says the Commission, means the UK is indirectly discriminating against nationals of another member state, in breach of EU social security co-ordination rules under which EU citizens have the same rights and obligations as nationals of their host country.