Eurozone finance ministers have rejected a Greek request to extend a bailout programme beyond 30 June.
A Eurogroup statement said Greece had broken off negotiations over a new bailout deal “unilaterally”.
Late on Friday, Greek PM Alexis Tsipras called a surprise referendum for 5 July over the terms of any new deal.
Greece has to pay €1.6bn (£1.1bn) to the IMF on Tuesday. Without new funds, there are fears Greece may leave the euro and its economy may collapse.
Eurogroup head Jeroen Dijsselbloem said finance ministers would reconvene to discuss the consequences of the latest developments.
They were determined “to maintain the strength and credibility of the eurozone”, he said.
It would be up to the European Central Bank (ECB) to decide whether to continue providing emergency liquidity funding to the Greek banking system, he added.
Greek Finance Minister Yanis Varoufakis said the Eurogroup’s refusal to extend the bailout could permanently damage the credibility of the group.
Mr Varoufakis said Greece had asked for an extension of “a few days, a couple of weeks”, whereas Mr Dijsselbloem said an extension of one month had been requested.