The largest member of the EU's emerging east has so far treated euro entry as a distant prospect. But top officials now fear they could be left out of what they see as Europe's core as the euro zone gets to grips with the three-year debt crisis.

"According to calculations carried out at the President's Chancellery, January 1 2016 is a realistic date for Poland's accession to the euro zone," Roman Kuzniar told radio RM FM.

"We must remember that the later we do it, the harder it will be, because the euro zone will have built itself up. There will be more criteria and more treaties to ratify in order to enter it in five, six or seven years."

Prime Minister Donald Tusk said on Friday that while actual adoption would still take years, the opportunity may "float away" if Poland did not take a decision in the coming months.

Part of Warsaw's concern is that the euro zone has begun to make far-reaching decisions to steady itself against the crisis.

Such moves include this week's EU decision to give the European Central Bank new powers to supervise banks.

Poland, the European Union's seventh-largest economy, is the only member to have avoided recession in the wake of the global financial crisis.

But that is in large part thanks to a huge weakening of its currency as the global crisis took off in late 2008, making its exports more competitive in international markets.

Convincing the country to give up that advantage will be no easy task. Polls show less than a third of the public favor abandoning the zloty for the euro, and the government will also have a hard time winning support from the opposition to push through the required constitutional changes.

(Reporting by Maciej Onoszko; Editing by Hugh Lawson)

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