IMF chief reassured on Greece after talks

But she also expressed concern over what she called "reform fatigue" in Greece and said "time is running short" for Greek authorities to deliver on conditions set in the country's massive bailout package.

Speaking in Washington, Lagarde called a statement issued after Wednesday's tele-summit between Greek Prime Minister George Papandreou, German Chancellor Angela Merkel and French President Nicolas Sarkozy "a clear indication from them... that the future of Greece is really in the eurozone."

She said she was "personally very reassured" by the post-talks statement which said both the French and German leaders "are convinced that the future of Greece is in the eurozone."

Greece's future in the common currency area "seems to be very strongly entrenched for both of them," Lagarde said after making a speech on global economic challenges in Washington.

The IMF managing director said the statement Wednesday "echoes" the commitments made by the eurozone members on July 21 to continue to support Greece, widely feared on the verge of defaulting on hundreds of billions of euros in sovereign debt.

One of the principles of those commitments, she said, is that as long as a member country is in difficulty and under a rescue program performs its obligations, "the members of the eurozone will support it financially, without a cap, without a limitation."

"That's a very strong and bold statement," she added.

The IMF is taking a key part in last year's 110 billion euro ($151 billion) bailout of Greece, but is still analyzing Athens's progress before releasing a new tranche of funds to the government.

The IMF has not committed to adding funds to the second-round bailout proposed in the July meeting of the European Union, European Central Bank, and private lenders.

In an interview with CNBC television Lagarde recalled that IMF funds releases are tied to countries meeting the conditions of its support programs.

"Implement (and) you will get payment of the next tranche."

She said the Greeks had made a "massive effort" to meet the conditions, but "It's a question of keeping at it.

"There was reform fatigue and the momentum slowed down."

"Time is running short and the Greek authorities have to deliver, have to come a little bit more bipartisanly, if they can, to make sure the country is on track," she said.