Financial markets are gripped by the fear Athens will not be able to service its heavy debt, putting pressure on the euro and even raising speculation as to whether Greece could be forced out of the currency bloc.

"This an attack on the euro zone by certain other interests, political or financial, and often countries are being used as the weak link, if you like, of the euro zone," Papandreou told the World Economic Forum in Davos.

"We are being targeted, particularly with an ulterior motive or agenda, and of course there is speculation in the world markets."

He said Greece was responsible for putting its own house in order, with the euro zone helping to maintain discipline.

Spanish Prime Minister Jose Zapatero, whose country holds the presidency of the European Union, backed Papandreou, insisting no country planned to leave the euro currency bloc or the broader European Union.

"No one is going to be leaving the euro, more countries are going to be joining," he told the same session at the annual meeting in the Swiss ski resort of Davos, adding that was the "best proof" of the project's success.

"The euro club is a strong club with strong ties and reciprocal support - let no one be mistaken."