UK Independence Party leader Nigel Farage has warned that some EU countries face "mass civil unrest, possibly even revolution" as a result of austerity cause by the euro crisis.
He told the European Parliament the rise of "extreme" parties "could cause the rebirth of National Socialism" in countries such as Greece.
Mr Farage, whose party wants the UK to leave the EU, urged an end to the eurozone project.
It was "headed the wrong way", he said.
In Greece, the leader of the left-wing Syriza bloc, Alex Tsipras, has tried to form a government following inconclusive elections on Sunday.
He has described the EU-International Monetary Fund bailout, and its resulting austerity measures, as "barbaric".
In the European Parliament, Mr Farage, who is an MEP for south-eastern England, said: "When people stand up and talk about the great success that the EU has been, I'm not sure anybody saying it really believes it themselves anymore."
He added: "This has all gone badly wrong and the EU Titanic has now hit the iceberg.
"It's a European Union of economic failure, of mass unemployment and of low growth."
Of the euro, Mr Farage also said: "This now poses huge dangers to the continent. We face the prospect of mass civil unrest, possibly even revolution in some countries that are being driven in to total and utter desperation...
"In Greece what we saw last Sunday was rather reminiscent of the German election of 1932. We saw the status-quo centre collapse and the extremes of Right and Left rise.
"This project could even cause the rebirth of National Socialism in Europe. We are headed the wrong way.
"We must break up the eurozone. We must set those Mediterranean countries free."