Greece talks need 'adults in the room': IMF's Lagarde

International Monetary Fund chief Christine Lagarde today warned that a resolution to five months of tortuous debt talks with Greece required "adults in the room" in an apparent sideswipe at Greek officials.

"For the moment we are short of a dialogue, the key emergency is to restore the dialogue with adults in the room," Lagarde said at a press briefing after the latest round of eurozone finance ministers' talks on the crisis broke up without a deal, less than two weeks before Athens must repay 1.6 billion euros to the IMF."

Her comment comes after Greek Prime Minister Alexis Tsipras said the Washington-based lender had a "criminal responsibility" for the Greek crisis.

"The IMF teams are available day and night. They stayed for entire weeks in Brussels and waited and are ready to return," Lagarde said, two weeks after the IMF pulled negotiators from technical talks with Greece because of the lack of progress.

"(Greece's proposals) cannot be about smoke and mirrors, it has to be credible," she added.

"The institutions have put together very sensible proposals," she said, 12 days before Greece's huge payment deadline.

"We are waiting and we hope that next few days will be used by the Greek government to come with tangible measures."

Greece had already bought itself time by bundling four looming IMF loan payments into one to be paid by the last day of June, becoming the first country to use such a possibility since Zambia in the 1980s.

Lagarde's refusal to consider an extension adds to the pressure on Greece's radical-left government as its creditors are refusing to dole out the last tranche of its international bailout, which also expires on June 30.