The International Monetary Fund on Thursday said "major differences" remain with Greece over an agreement to save the country from bankruptcy, in some of the Fund's strongest comments yet on the negotiations.

"There are major differences between us in most key areas," IMF spokesman Gerry Rice told reporters. "There has been no progress in narrowing these differences recently, and thus we are well away from an agreement."

He said the IMF's technical team has returned from Brussels, where it had been talking with Greek officials, but emphasized that the Fund remains "fully engaged" with Athens.

U.S. stocks pared their gains on the news.



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Rice said it appeared Greek officials were seeking solutions "at the political level," with other Europeans ministers.

European Union officials described talks between EU chief executive Jean-Claude Juncker and Greek Prime Minister Alexis Tsipras which ended earlier on Thursday without agreement as a "last attempt" to reach a debt deal.

Asked about concerns for the process raised by the departure of IMF and Greek negotiators from Brussels, an EU diplomat said:

"If the process was working properly the president would not have had to have a meeting with Tsipras today. President Juncker made a last attempt to make a deal possible."

The leaders of Germany and France agreed with Greek Prime Minister Alexis Tsipras on Wednesday that negotiations between Greece and its creditors must be intensified to reach a deal to avert a Greek default but there was no sign of a breakthrough.

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The talks have been deadlocked over Greece's rejection of the creditors' demands for cuts in pensions and unpopular labor market reforms as conditions for releasing frozen bailout funds.

The IMF's Rice said the main obstacles are around pensions, taxes and financing.

Greece is likely to default at the end of June if it does not receive fresh funds to enable it to make a 1.6 billion euro repayment to the International Monetary Fund.

—CNBC contributed to this report.