Belgian Finance Minister Johan Van Overtveldt said the eurozone's credibility would be damaged if past accords with Greece were changed.

The European Commission said it would only resume mediation efforts if Greece put forward new proposals, while the Greek government spokesman said Athens was sticking to its rejection of wage and pension cuts and higher taxes on basic goods.

"We have largely exhausted our limits," spokesman Gabriel Sakellaridis said. Tsipras' office said Greece was ready to restart talks at any time and was waiting for a signal from lenders that could loosen the deadlock.

"If they call us with something new, we may also provide something new," one official said.

Despite the deepening crisis, Tsipras is going ahead with a planned visit to Russia from Thursday, the day eurozone finance ministers hold a crucial meeting to review the standoff with Greece. He is due to stay till Saturday, attend an economic forum in St. Petersburg and meet President Vladimir Putin.

EU officials said that without improved Greek proposals by Thursday, the Eurogroup session would be very tough and was likely to present Greece with an ultimatum.

"No more new proposals; take it or leave it time is upon us, I think. Or very close." one eurozone official said.

While there was little outward sign of panic in Athens as Greeks held out hope for a last-minute solution — a familiar theme in five years of crisis — the latest impasse triggered a selloff in European and Asian shares and weighed on the euro.

Greek banks suffered deposit outflows of about 400 million euros ($449 million) on Monday as the pace of daily withdrawals picked up from last week, bankers said.

European Central Bank President Mario Draghi said the ECB would keep approving emergency lending to Greek banks as long as they remained solvent but would monitor closely whether they had sufficient collateral.

Draghi stressed in testimony to the European Parliament it was up to elected politicians, not to central bankers, to decide on Greece's fate and the ECB could not allow its liquidity to be used illegally to finance the Greek government.

"While all actors will now need to go the extra mile, the ball lies squarely in the camp of the Greek government to take the necessary steps," Draghi said.

Reuters