U.S. dollar fell to the lowest level in 2017 against Turkish lira at 3.4151 on Thursday while continuing its retreat against the euro and developing economies' currencies.

The parity rate began trading at 3.43 level early in the day, and fell below the 3.42 level in the afternoon.

The fall was accelerated as the European Central Bank (ECB) kept its key interest rates unchanged at 0 percent and stuck to its bond purchase stimulus program at Thursday's meeting in line with market expectations.

The Chinese yuan climbed above a key rate of 6.5 per dollar for the first time since May 2016 as a U.S. debt ceiling deal and receding prospects of Fed rate hikes boosted risk appetite.

Reports suggesting that the "hawkish" U.S. Fed Vice Chairman Stanley Fischer considering to resign next month also accelerated the losses of the U.S. dollar.

The dollar had reached a historic high against the lira on Jan. 10 at 3.8950.