Greece says it cannot make any more concessions, as it races to clinch a last-minute debt deal with its creditors.
“There is no room for more compromises,” said Labour Minister Panos Skourletis.
He also said that international lenders must take responsibility for their role in continuing negotiations.
The clock is ticking ahead of a Friday deadline, when Athens is due to make a 300-million euro repayment to the International Monetary Fund.
There are growing doubts about whether it will be able to foot all of its bills this month.
The potential consequences are a default and a departure from the eurozone.
German Chancellor Angela Merkel has hosted late-night talks with French President Francois Hollande and finance bosses in Berlin.
They have agreed to work with “real intensity” to hammer out a deal.
The Greek government has re-iterated that it cannot sign any agreement that’s in conflict with its anti-austerity programme.
In a recent newspaper article, Prime Minister Alexis Tsipras accused lenders of making “absurd proposals” and disregarding Greek democracy.