Greece says it aims to clinch by Sunday a deal with creditors to get more rescue loans.

Government spokesman Gabriel Sakellaridis told reporters at a briefing on Thursday that "we are going into these negotiations with the aim to have a deal by Sunday."

Reports from Greece Wednesday that a deal was near caused a market rally, but the optimism proved short-lived as key creditor states, like Germany, quickly warn that a final agreement remained elusive.

Greece has been in talks for four months on what reforms it should make to get the final installment of its bailout program, worth 7.2 billion euros ($8 billion) from fellow eurozone states and the International Monetary Fund. Without the money, it will be unable to pay debts due as soon as June 5.