Jean-Claude Juncker has slapped down David Cameron for his constant attacks on EU migrants.
The Brussels chief accused the Tory PM of "beating up" workers from eastern Europe to win votes.
"In Great Britain there has to be an end to discrimination against countries just because it goes down well topically when you beat up others," Mr Juncker fumed.
"I am utterly against behaving as if all Poles, all Romanians, all Bulgarians in the European labour market are of a basic mentality that is criminal.
"These are people who are working and earning their wages."
Mr Cameron and Mr Juncker have been at loggerheads since the PM tried to block the former Luxembourg premier's appointment as head of the European Commission.
But Mr Cameron now wants backing for his plan to limit the number of EU migrants who move to Britain.
In a major speech on immigration last month the PM said he would ban new arrivals from receiving benefits for four years and deport people after six months if they do not have a job.
But he stopped short of demanding a so-called "emergency brake" on the total number of new arrivals.
Mr Juncker warned the PM that people's basic right to work in different countries around Europe was not up for negotiation.
"This fundamental right of free movement of workers cannot be questioned," he said.
But he made clear he was happy to discuss Mr Cameron's plans for reform.
"We did not shoot down these ideas right away because I believe that we have to talk about them," Mr Juncker said.
"I am really interested in Great Britain remaining an active and constructive member of the EU."
Mirror.uk
