UPDATE 1-Ukraine surprises with aggressive interest rate hike

(Adds quote, background on expectations)

KIEV, Jan 25 (Reuters) - The Ukrainian central bank unexpectedly raised its key rate to 16 percent from 14.5 percent on Thursday, its third consecutive rate change to contain stubbornly high inflation.

"The tighter monetary policy will help decrease inflation and bring it back to the target range in the middle of 2019," it said in a statement.

The central bank could continue to raise the main interest rate if there are no signs of inflationary pressures easing in the short term, the statement said, adding that rising food prices and household incomes remains a key inflation risk in 2018.

Inflation stood at 13.7 percent as of end-December, after hitting a 2017 high of 16.4 percent in September partly due to higher fuel costs and a fall in the hryvnia currency.

Economists had mostly predicted that the central bank would keep rates on hold, according to a Reuters poll published on Jan. 4.

"In the absence of indications of the lowering inflationary pressure the NBU may further increase the key policy rate to return inflation to its medium-term target," the National Bank of Ukraine said in its statement. (Reporting by Natalia Zinets; Writing by Alessandra Prentice; Editing by Matthias Williams and Alison Williams)