Rift with Greece sets Europe into uncharted territory

* Euro zone, Greece face off after months of "poker"

* Anger at Greek government evident, despite fear of risks

* Unclear how coming days will affect currency bloc

* Wider concerns raised about future of European Union

By Alastair Macdonald

BRUSSELS, June 28 (Reuters) - Europe's grand project to bind its nations into an unbreakable union by means of a common currency lurched into uncharted waters after EU governments refused funding to save Greece from defaulting on its debts.

While finance ministers of the other 18 euro zone states chorused their insistence that Greece would remain inside the bloc, exasperation with the leftist government's decision to reject creditors' final offer and instead call a referendum was manifest and some officials spoke privately of expelling Athens.

"They were playing poker," said Austrian Finance Minister Hans Joerg Schelling after the Eurogroup that runs the currency met on Saturday without their Greek counterpart to discuss how to limit the fallout. "But in poker, you can always lose."

After five months of halting negotiations with a Greek government elected to end the pain of austerity measures, EU leaders left a summit in Brussels on Friday believing that a deal was close to roll over bailout funding and let Athens meet a repayment to the IMF on Tuesday and further obligations over the coming months.

But Prime Minister Alexis Tsipras provoked consternation by returning home to call a referendum for next Sunday on the offer and urging voters, weary of years of debt crises, to reject it.

"Tsipras messed up," one EU official said. "We did everything possible. They chose to blow up when we were so close to settling this in a way that would allow them to sell it."

Amid political drama in Greece, where a clear majority wants to remain inside the bloc, the next few days present a major challenge to the integrity of a 16-year-old currency bloc, which many blame for massive unemployment in countries outside Germany and its neighbours in the richer north and west of Europe.

RISK MANAGEMENT

"We must do everything we can to fight any conceivable threat of contagion," German Finance Minister Wolfgang Schaeuble said after a meeting at which the group effectively called for capital controls to ring-fence Greek banks haemorrhaging cash.

While acknowledging that only Greece - or possibly banks themselves - can instigate such a shutdown, the ministers said the European Central Bank, whose management meets on Sunday, should use its powers to stabilise markets.

"You have to count on Greece getting into acute problems in the coming days because of this decision," said Schaeuble, some of whose conservative allies have made no secret of preferring to see Greece forced out of the euro zone. "That is difficult as we do not know how it will live up to its commitments."