A warning by Greece's central bank that the country risked being driven from the euro zone and, ultimately, the European Union failed to break a deadlock with creditors before a potentially decisive meeting of European finance ministers.
A top Greek negotiator told Reuters Athens was ready to make unspecified concessions, but once again ruled out any cuts to pensions - a major sticking point in the negotiations. Germany, the euro zone's most powerful economy, stuck to its line that Greece had to make significant moves to break the stalemate.
Athens has until the end of June to find a way out of the impasse before it faces a 1.6 billion euro ($1.8 billion)repayment due to the International Monetary Fund, potentially leaving it bankrupt and teetering on the edge of the euro zone.
"It won't work without Greece moving significantly," German Foreign Minister Frank-Walter Steinmeier said in Berlin.
Greek negotiator Euclid Tsakalotos confirmed that Greece does not have the money to repay the IMF and said the leftist government would only accept a deal that was sustainable and addressed debt, financing and investment - issues the European Union has said it does not want to open at this stage.
"If you have that, then the Greek government will sign the deal," Tsakalotos said. "If it doesn't have that kind of deal there is no point in signing onto something that you know is going to fail."
Hopes that a deal might be struck on Thursday at a meeting of European finance ministers looked increasingly remote.
"People are getting anxious on both sides. Athens expects Brussels to move. And Brussels expects Athens to move. And it's stuck," said a senior EU diplomat, who declined to be named.
"It's very dangerous, and we may have an accident."
Making clear the huge stakes at play, the Greek central bank said reaching an accord was "an historical imperative" that the country could not ignore.
"Failure to reach an agreement would ... mark the beginning of a painful course that would lead initially to a Greek default and ultimately to the country's exit from the euro area and, most likely, from the European Union," the Bank of Greece said in a monetary policy report.
Greek Prime Minister Alexis Tsipras accused the creditors on Tuesday of trying to "humiliate" his country by demanding more budget cuts to unlock desperately needed frozen aid.
Elected in January on a pledge to end years of grinding austerity, Tsipras wants his European partners to re-negotiate Greece's debt mountain, but they have ruled that out for now and instead want to see a fresh round of economic reforms, including pension cuts, to help the state balance its books.
"...If we don't have an honourable compromise and an economically viable solution, we will take the responsibility to say 'no' to the continuation of a catastrophic policy," Tsipras said after meeting Austrian Chancellor Werner Faymann.
Faymann, one of the European leaders most sympathetic to Athens, flew to Greece seeking a last-ditch deal.
"I can't see a solution lying before me, but I see that if we are convinced we want one, we have a good chance," he said.
Months of uncertainty have already taken their toll. After years of recession, Greece's economy finally started to grow again last year, but it fell back into negative growth in the first quarter of 2015 and Greece's central bank predicted the slowdown would accelerate in the second quarter.
The ongoing crisis has prompted an outflow of deposits totalling about 30 billion euros ($33.84 billion) from Greek lenders between October and April, the bank said.
Some officials believe Thursday's meeting of euro zone finance ministers will be perhaps the last chance to stop Greece sliding into default and towards leaving the euro.
However the president of the so-called Eurogroup, Jeroen Dijsselbloem, said the chance of an accord was "very small".
EU officials have expressed frustration with what they see as Greece's failure to provide viable or detailed reform plans. The International Monetary Fund pulled its negotiators out of the talks last week citing the lack of any clear progress.
Highlighting the fraying tempers, German Chancellor Angela Merkel's Bavarian allies accused Athens on Wednesday of not grasping the seriousness of the situation, with CSU Secretary-General Andreas Scheuer calling Greek rulers "clowns".
The Greek central bank urged the European Union to spell out promises of debt relief to Greece - a key demand from Athens.
"An agreement would allow Greece to benefit from the favourable global environment and the ECB's quantitative easing programme," the report said.
The British government is accelerating its preparations for a possible Greek exit from the euro zone, a spokeswoman for Prime Minister David Cameron said on Wednesday, after the Greek central bank warned of the consequences of such a scenario.
The Greek central bank warned on Wednesday that the country would be put on a "painful course" towards default and exiting the euro zone if the government and its international creditors failed to reach an agreement on an aid-for-reforms deal.
Jean-Claude Juncker rebuked Greek Prime Minister Alexis Tsipras on Tuesday, accusing him of giving his voters a deliberately distorted version of proposals the EU chief executive had made to resolve Athens' debt crisis.