Some eurozone countries no longer want Greece in the bloc, Finance Minister Evangelos Venizelos has said.
He accused the states of “playing with fire”, as Greece scrambled to finalise an austerity plan demanded by the EU and IMF in return for a huge bailout.
Mr Venizelos promised to clarify the plan before a conference call with eurozone bosses due at 16:00 GMT.
Greece needs to convince lenders that it will make enough savings, and that its politicians will enact the changes.
Athens is hoping to get a 130bn-euro (£110bn; $170bn) bailout from the EU and IMF.
The deal also includes a provision to write off a further 100bn euros of debt owed to banks.
Parliament approved a package of austerity measures on Sunday, but eurozone ministers indicated that more detail needed to be given on the cuts.
The ministers also insisted that the major Greek political parties committed to implementing the cuts, regardless of who wins a general election scheduled for April.
Leaders of the two main parties have now signed letters committing them to enacting the changes.
The leader of the conservative New Democracy party, Antonis Samaras, wrote that if his party won in April it would “remain committed to the programme’s objectives, targets and key policies”.
But he said that “policy modifications might be required to guarantee the full programme’s implementation”.
An official told the BBC that 325m euros of extra savings had been made with cuts from defence, health and local government budgets.
Mr Venizelos said there were “very few remaining issues” with the austerity package and promised to have them “fully clarified” before the conference call.
But he also warned that some eurozone countries were “playing with fire”, saying: “There are many in the eurozone who don’t want us any more.”
Mr Venizelos also said that President Karolos Papoulias had volunteered to give up his salary as an “honourable… symbolic gesture”. He is reported to earn 280,000 euros a year.
‘False rumours’Without the bailout, Greece will be unable to pay its debts and will be forced into a default.
Its next payment is due on 20 March, and the complex technicalities of finalising the bailout will take several weeks even after the politicians have agreed the measures.
But the austerity plan has been hugely unpopular in Greece.
Greece crisis in numbers
Sources: ELSTAT, BBC
Anger boiled over during Sunday’s vote in parliament, when large groups of protesters clashed with riot police and dozens of buildings were set on fire in Athens.
And eurozone countries appear to be running out of patience with Greece.
On Wednesday German Finance Minister Wolfgang Schaeuble told local radio he wanted to help Greece, but “we are not going to pour money into a bottomless pit”, in comments translated by the AFP news agency.
And unnamed eurozone officials were quoted suggesting that Greece’s latest assurances still may not be enough, because people no longer trusted the country’s politicians.
Greece has failed to deliver on many of the promises it made to secure an earlier bailout deal, EU officials say.
In a press briefing on Wednesday, German Chancellor Angela Merkel’s spokesman, Steffen Seibert, denied Germany wanted Greece out of the eurozone.
“I can clearly state for the federal government that these rumours are false,” he said.
Amadeu Altafaj, a spokesman for EU economics commissioner Olli Rehn, said eurozone members had “stated very clearly that they want Greece to remain a member of the eurozone”.
However, the BBC’s Matthew Price in Brussels says there is a growing sense among eurozone members that if Greece did leave it would not mean the collapse of the euro.
And in an interview in Manager Magazin to be published on Friday, the head of Germany’s engineering and electronics giant Bosch calls for Greece to be ejected from the EU.
In a transcript acquired by Reuters, CEO Franz Fehrenbach says: “This state with its phantom pensioners and rich people that don’t pay taxes, a state without a functioning administration, has no place in the European Union.”