Athens wants the ECB to increase the liquidity lifeline and permit the banks to buy more short-term treasury bills, easing the government's immediate funding crunch. Greece has already commandeered cash reserves from municipalities and government bodies as it scrapes together funds to repay 970 million euros to the IMF by May 12.
But euro zone central bank sources say hardliners led by Germany's Bundesbank want the "haircut" on Greek securities offered as collateral for the funding to be increased following recent credit rating downgrades of Greece and its banks.
One such source said he did not expect the council to make a dramatic change that would put Greek banks in immediate difficulty while negotiations are continuing.
The political uncertainty was enough to prompt the European Commission to slash its forecast for 2015 Greek economic growth to 0.5 percent from 2.5 percent just three months ago and cut its estimate for the primary budget surplus before debt service.
A Financial Times report that the IMF's European chief Poul Thomsen had threatened to cut a funding lifeline to Greece unless its European partners agree to a debt write-off was denied by German Finance Minister Wolfgang Schaeuble.
"The IMF of course did not make such a comment," Schaeuble said, though Thomsen did say things "had become more difficult".
An IMF spokesman denied in a statement that the global lender had pushed for large-scale debt relief at the meeting of euro zone finance ministers in Riga on April 24.
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However, Thomsen had "pointed to the tradeoff that needs to be made" between Greece's slippage from fiscal targets agreed in 2012 and the additional financing and debt relief needed to make the country's debt sustainable, he said.
The report had sparked a sell-off in Greek bonds and stocks while worries about Greece helped drive European shares lower.
While Germany and its allies have pointed to calm in bond markets to suggest that a Greek default or exit from the euro zone would not cause a wider financial meltdown, as it might have done in 2012, other EU countries are more concerned.
Moscovici stressed on Tuesday the Commission's goal was to keep Greece in the euro zone and avert what he called an "accident", while Italian Foreign Minister Paolo Gentiloni warned against belittling the risks of a possible "Grexit".
"Italy's government considers it short-sighted and dangerous to underestimate the Greek crisis," Gentiloni told reporters, adding that the idea of a Greek exit from the euro zone could not be taken lightly.