The IMF dashed any hope on Thursday that Greece could avert default if it fails to repay a 1.6 billion euro ($1.8 billion) loan by the end of June, piling pressure on leftist Prime Minister Alexis Tsipras, who showed no sign of yielding to creditors' demands.

Eurozone finance ministers descended on Luxembourg for a meeting once billed as the final chance to reach a deal, but any expectation of a breakthrough there had all but vanished, with Athens ruling it out as a forum to discuss new proposals.

Ireland's finance minister said he expected any chance of a last-ditch deal to avert a Greek default to hinge on a European Union leaders' summit late next week.