European Council President Donald Tusk warned Greece has just five days left to reach an agreement to save it from bankruptcy ahead of an emergency summit on Sunday involving all 28 EU members.
"The stark reality is that only have five days to find the ultimate agreement," he said.
"Until now I avoided talking about deadlines, but tonight I have to say it loud and clear - the final deadline ends this week. All of us are responsible for the crisis, and all of us have a responsibility to resolve it."
President of the European Commission Jean-Claude Juncker warned that the EU has already laid out detailed plans in the event of a Grexit.
"I am strongly against Grexit but I can't prevent it unless the Greek government do what they need to," he said.
"We have a Grexit scenario prepared in detail."
Tusk and Juncker were speaking at a press conference following tonight's emergency Eurozone summit meeting at which Prime Minister Alexis Tsipras launched a bid to win new aid from the country's creditors.
Unconfirmed media reports suggested Greece is proposing an interim funding agreement to tide the cash-strapped country over, followed by a longer one.
But Eurozone finance ministers were shocked earlier after Greece failed to bring any new proposals to a preparatory meeting before the summit.
The cash-strapped country's new finance minister Euclid Tsakalotos had previously suggested it would submit a new proposal as soon a Tuesday night.
Meanwhile, Eurozone leaders gave mixed signals regarding what to expect from Sunday's meeting involving all 28 EU members.
"Next Sunday the final meeting will take place on Greece ... I am not pessimistic," Italian Prime Minister Matteo Renzi said.
However, German chancellor Angela Merkel said she was not “not especially optimistic.”