BERLIN (Reuters) - Polish Prime Minister Donald Tusk said on Monday he wanted his country to join the euro "as soon as possible" although a majority of his compatriots had concerns about such a step because of the euro zone debt crisis.

Adopting the euro has been a central goal for Tusk since coming to power in 2007 but he recently signaled that he was ready to back a referendum on the issue, which could complicate the plan to join the common currency.

"A majority of the population has concerns based on what is happening in the euro zone," Tusk said in Berlin, where he was attending a book launch with German Chancellor Angela Merkel, a close ally on the European political stage.

(Reporting by Noah Barkin; Writing by Gareth Jones; Editing by Stephen Brown)