The European Union (EU) will do its utmost to prevent Greece from defaulting on its mountain debts, president of the 27-nation bloc said on Wednesday.

"We will do our utmost not to face default, or a credit event," European Council President Herman Van Rompuy said at a press conference shortly before he joins the leaders of the Group of Eight (G8) industrialized nations for an annual summit in the French seaside resort of Deauville.

Van Rompuy said he would update the other G8 leaders on the latest development of the sovereign debt crisis in the eurozone, which has dragged on for more than one year and engulfed Greece, Ireland and Portugal so far.

Despite being bailed out by the EU and the International Monetary Fund (IMF) with 110 billion euros (around 155 billion U.S. dollars) in May last year, Greece is now widely expected to restructure its debts sooner or later as its economy continues to shrink due to stiff austerity measures demanded by international lenders.

Technically speaking, Van Rompuy said, any restructuring of Greek debts would mean a default, which may cause chaos in the financial markets and add pressure on Ireland and Portugal.

The EU is treading carefully with the prospect of a Greek debt restructuring. EU officials have so far tried to avoid using the word "restructuring" and picked up other tricky terms.

Eurogroup President and Luxembourg Prime Minister Jean-Claude Juncker said on Tuesday that Greece may negotiate with private bond holders on an extension of repayment if the debt-laden country fulfils all reform and budget targets.

"If all these conditions are met, we cannot exclude a reprofiling, meaning that there could be a lengthening of the payback period for the loans," Juncker said.

Experts said a debt reprofiling, or soft restructuring which would result in later payment but would not reduce the value of the debts, could be regarded as a non-credit event, not a default, if it is agreed with creditors on voluntary basis.

Van Rompuy said EU leaders would not let the euro fail in the sovereign debt crisis and he is cautiously optimistic despite the fact that the European single currency is still going through difficult times.

"That is why the emphasis must continue to be on implementing the tough but necessary reforms and create the basis for sustained growth and employment," he said.

The EU president urged Greece to take all necessary measures to implement reforms so as to avoid a default, which he said is still doable.

Van Rompuy said the EU will work with the IMF and its members, notably the United States, in the battle against the euro's toughest challenge, but he ruled out that any negotiation on the solution to the crisis may happen at the G8 summit, which lasts till Friday.

"We are not here to negotiate anything," he said.