Eurogroup chief Jeroen Dijsselbloem late Monday stopped short of giving any specific figures regarding the size of the fiscal gap in Greece's adjustment program.
"The present EU mission has not been finalized. So, for me, it's too early to say and I could certainly not pin any number on it," Dijsselbloem said at a press conference after a meeting of eurozone finance ministers.
"There are fiscal issues which have to be addressed still, but I was a bit surprised by the numbers I was hearing before the meeting," said Dijsselbloem in response to media questions.
Earlier Monday, European Central Bank (ECB) Executive Board member Joerg Asmussen, speaking to reporters before the Eurogroup meeting, urged Greece to take measures to plug a hole in its 2014 budget plan.
"It's first and foremost important that they close their significant fiscal gap that is there for the next year," Asmussen told reporters.
The ECB official said a financing gap of five billion euros (about 6.8 billion U.S. dollars) to 6 billion euros has opened in the second half of 2014 under Greece's international rescue program.
Greek Finance Minister Yannis Stournaras late Monday rejected the "allegation" made by Asmussen that Greece faces a "significant fiscal gap."
"There is no significant fiscal gap," Stournaras told reporters after the meeting of euro area finance ministers, while admitting that, "We do have fiscal challenges, always."
Greece is "on course to post a budget surplus excluding interest payments," he added.
The Greek finance minister put the financing gap in the second half of next year at "around 5 billion euros," and said that the eurozone finance ministers had an "initial discussion" about it at their meeting.
Stournaras said all options are being considered to plug the hole and he expected a decision in late December.
While Asmussen insisted "there is absolutely no way that it can be done in a way of roll-over bond," Stournaras said, "All the ideas came on the table. Nothing is off the table."
EU Economic and Monetary Affairs Commissioner Olli Rehn said that discussions over Greece's fiscal gap, and any shortfall in aid funding, would continue over the "coming weeks."
Dijsselbloem, who also serves as the Dutch finance minister, praised the "considerable consolidation efforts" made by Greece and the fact that it may achieve a primary surplus by the end of the year.
"We hope to be to take stock of the outcome of the current review for Greece at our meeting in December or January - including any financing gap until the end of the programme next year," the Eurogroup head said.