The head of the European Commission has warned that the urgency of the eurozone crisis is "not fully understood" by some national governments.

Citing a "social emergency" and urging ever greater union, José Manuel Barroso told the European Parliament that it is a defining moment for European integration.

He was speaking in the run-up to a 28-29 June summit of EU leaders, with Italy now under rising pressure of the type that eventually forced external financial aid on Spain.

"Even when governments take the right steps to reform, these can be negatively impacted by events outside their control," Mr Barroso said.

"We must recognise we have a systemic problem. We need a vision and a concrete path. I am not sure the urgency of this is fully understood in all the capitals," he said.

Meanwhile, Britain's finance minister George Osborne has suggested that Europe may need to sacrifice Greece's membership of its single currency in order to convince Germany to put in more money to save the euro.

As the EU's biggest economy and largest contributor, Germany holds the key to how the bloc can rescue its troubled, smaller economies and whether Europe is able to agree on a banking union to end years of debt turmoil.

Britain and the rest of the EU have clashed repeatedly over how to fix the crisis, with London refusing bluntly to take any part in any banking union.

"I ultimately don't know whether Greece needs to leave the euro in order for the eurozone to do the things necessary to make their currency survive," Mr Osborne said in remarks published in The Times newspaper in Britain today.

"I just don't know whether the German government requires a Greek exit to explain to their public why they need to do certain things like a banking union, euro bonds and things in common with that."

Despite its tough rhetoric, Britain is in an awkward position in its dealings with the EU because it is not a member of the eurozone, yet the fate of its economy is tied closely to the future of the single currency bloc.

Yesterday, Herman Van Rompuy, chairman of the EU leaders' meetings, said the bloc would do all it can to keep Greece in the eurozone if it respects its bailout commitments.

Mr Osborne's comments came just days ahead of an election in Greece seen widely as a referendum on whether it should stay in the eurozone, or leave and go back to its old drachma currency.

Eurozone rescue funds are already stretched by supporting Greece, Portugal, Ireland and now also Spain, after finance ministers agreed to lend it up to €100 billion to recapitalise its banks.

Mr Osborne - who had earlier urged the eurozone to use its bailout fund to recapitalise Spain's troubled banks directly - described the deal as "too little, too late".

"If you do it via the Spanish sovereign, then you are not going to convince the market the Spanish sovereign is entirely credible...and yet they went ahead down this route," he said.