European Commission President Jean-Claude Juncker said Sunday that Athens had so far failed to provide a list of alternative reforms, after Greece's premier rejected its creditors' demands as absurd.
"Alexis Tsipras, my friend, had promised that by Thursday evening, he would present a second alternative proposal... I have never received this alternative proposal," said Juncker.
Greece's radical-left government and its creditors -- the International Monetary Fund, the European Union and European Central Bank -- have been negotiating for five months over unlocking 7.2 billion euros (US$8 billion) in rescue funds that Athens desperately needs.
With the clock ticking down to debt servicing payments totalling 1.6 billion euros in three weeks, the creditors this week put a proposal to Greece that was hammered out without Athens at a meeting in Berlin.
Greek premier Tsipras said early on Thursday there were "points that no one would consider as a base for discussion" and that Greece's own reform plan remained "the only realistic plan on the table".
He told parliament a day later that "it is clear that the Greek government cannot under any circumstances consent to absurd proposals."
In turn Juncker on Saturday spurned Tsipras's request for a telephone conversation, with a spokesman reportedly saying that there was "nothing to discuss" given the lack of progress.
"Alexis Tsipras is my friend but friends have to observe minimal rules," said the EU president on the sidelines of the G7 summit in Bavaria.
He added that he "would like to see a Greek alternative proposal, I would like to have time to study it in detail".