International Monetary Fund Managing Director Christine Lagarde said Wednesday that a new program to prop up Greece's finances would require creditors to restructure debt.

In addition to the reforms Athens needs to undertake, she said, "The other leg is debt restructuring, which we believe is needed in the case of Greece for it to have debt sustainability."

"Greece is in a situation of acute crisis which needs to be addressed," she told a conference in Washington.

"We remain fully engaged in order to help find a solution."

In a report last week the IMF said Greece's official EU creditors should double the payback period for Greece's debts and also stump up another 36 billion euros ($40 billion) to ensure the country's finances remain sustainable.

But the European Commission and the European Central Bank are pressing the country hard to accept a package of austere fiscal and policy adjustments that Athens has so far refused to accept.