Urgent talks between Greece's Prime Minister, Alexis Tsipras, and the country's international lenders have ended without agreementon how to solve its debt crisis, officials say.
Eurozone finance ministers, who had been due to finalise a deal, will now discuss a plan proposed by creditors.
Greece's Yanis Varoufakis will attend and argue Athens' counter-proposal.
Time is running out to secure a deal. Greece must repay a €1.6bn (£1.1bn) IMF loan by next Tuesday or face default.
That could lead to Greece exiting the eurozone, with possible repercussions for the rest of Europe and the world economy.
Only once agreement is reached will the European Commission, the European Central Bank (ECB) and the International Monetary Fund (IMF) unlock the final €7.2bn tranche of bailout funds for cash-strapped Greece.
The crisis threatens to overshadow the EU summit opening on Thursday afternoon.
Sticking to proposalsEurogroup head Jeroen Dijsselbloem said finance ministers would be using the creditors' plans as a basis for an agreement.
"The only thing we have presented to the Eurogroup is what the institutions have made together," he said.
"We don't have agreement from the Greeks on that so we will have to hear in the Eurogroup meeting from the Greek side what their ideas are, what they could agree to, what they could not agree to and we'll take it from there."
Meanwhile Greek officials said Athens would be sticking to its own proposals, presented on Monday.