BRUSSELS — International creditors sent Greek Prime Minister Alexis Tsipras home from a summit Thursday with a clear message: Swiftly tone down your demands in the bailout talks over the next week or face financial ruin.

The International Monetary Fund took the toughest stance, saying it was bringing its negotiators back to Washington as there had been no sign of compromise.

“There has been no progress in narrowing these differences,” IMF spokesman Gerry Rice said Thursday. “There are major differences between us in most key areas.”

The creditors – the IMF and Greece’s fellow eurozone states – want the country to commit to new economic reforms before they pay out another 7.2 billion euros ($8.2 billion).

Athens needs the money to repay debts worth 1.6 billion euros at the end of the month and this summer.

European Union President Donald Tusk earlier warned “there is no more time for gambling” and that next week’s meeting of the 19 eurozone finance ministers in Luxembourg should be the make-or-break session in sealing Athens’ fate.

Cutting through days of dense diplomatic talk about the state of negotiations, Tusk said it was time for Tsipras to stop biding for time with unworkable demands.

“The Greek government has to be, I think, a little bit more realistic,” Tusk said.

The comments dented optimism created earlier in the day. Stock markets across Europe that had earlier rallied lost much of their gains. The Greek market closed up by a hefty 8.1 percent before the IMF’s tough statement.

Despite the bluster, the financial and economic stakes are such that cutting Greece loose from the eurozone or the global financial network seems improbable. Failing a deal, there have been fears that Greece could drop out of the euro, a move that would create huge uncertainty for Europe and global markets.

“We remain engaged,” Rice said. “The IMF doesn’t leave the table.”

For months, Greece has wrangled with its creditors over the release of the bailout loans.

European Commission President Jean-Claude Juncker said a two-hour meeting with Tsipras on Thursday had been “important, interesting and friendly” but he reported no breakthrough.