A European Commission spokesperson has said a country's membership in the eurozone is "irrevocable," when asked about Greece's possible exit from the single currency union following elections this month.
"Euro membership is irrevocable," Annika Breidthardt told reporters, saying the rule was enshrined in article 140, paragraph 3 of the Lisbon Treaty.
However, when asked whether such an option was feasible, commission spokesman Margaritis Schinas said: "We are not going to enter into speculation and scenarios which risk being interpreted in a context that is not put forward."
The commission, the executive arm of the EU, was questioned after the German weekly Der Spiegel reported on Saturday the German government believed it was inevitable that Greece would leave the eurozone if Syriza, the far-left anti-austerity party, wins the 25 January elections.
Syriza, which leads in opinion polls, has threatened to renegotiate the terms of its bailout if it wins the election, a prospect that has shaken the commission and the financial markets.
Greek Prime Minister Antonio Samaras has said the snap election would determine whether his country remains in the eurozone.
Earlier, French President Francois Hollande said countries including Spain and Greece had paid a heavy price to stay in the euro and it was "up to the Greeks" to decide whether to now remain a part of the single currency.
Following the reports at the weekend, Germany's economy minister later said Germany wanted Greece to remain in the eurozone and there were no plans to the contrary.
"As for Greece remaining in the euro zone, Greece alone can decide," Mr Hollande said.
"At this time we should not hypothesise about whether, according to the Greek vote, they would not or would still be a member of the eurozone. The Greeks are free to determine their own destiny."
