The central bank said late Thursday in a statement on its website that it had "sold a certain amount of foreign currency for zlotys." It gave no further details.
The zloty has depreciated significantly this year against major currencies like the dollar, euro and Swiss franc. The central bank and the state-run Bank Gospodarstwa Krajowego have intervened several times in recent months to shore it up.
The intervention caused the zloty to strengthen from about 4.46 zlotys to the euro in the early afternoon to about 4.41 after the bank’s move.