By Patryk Wasilewski And Martin M. Sobczyk 

WARSAW--Poland's central bank slashed its main interest rate by 50 basis points to 1.50%, the lowest on record, in response to persistent declines of consumer prices despite healthy economic growth.

Most analysts--17 out of 20 polled by The Wall Street Journal--had predicted a smaller cut of 25 basis points, with two expecting a deeper, 50 basis point cut and one saying rates would remain unchanged.

The central bank governor, Marek Belka, had flagged a possible cut in early February, when he said enough factors supported a lowering of interest rates.

The rate cut is the latest in a series of easing measures by central banks across Europe, following the European Central Bank's decision in late January to launch a program of quantitative easing, under which it will buy more than EUR1 trillion ($1.12 trillion) of mostly government bonds by September 2016.

Poland's consumer prices have been depressed for months, mainly because of the falling prices of food and oil in international markets, with consumer price inflation well into negative territory at -1.3% in annual terms in January. The central bank's target is an inflation rate of 2.5%.

The cut on Wednesday came despite a series of data suggesting the Polish economy is growing at a sustained pace. In 2014, it grew 3.3% and the central bank expects the rate of growth to remain above 3% over the next two years.

A central banker crucial to some recent rate decisions, Elzbieta Chojna-Duch, said in February the fall in consumer prices stems from factors beyond the Polish central bank's control and "as a principle" she was against moving rates further down. Still, an interest rate disparity between Poland and the eurozone, which has its rates near zero, is a factor that needs consideration, she also said at the time.

The U.S. dollar has appreciated around 6% against the zloty so far this year and around 16% over the last six months. After the rate decision, the zloty rose to 3.7584, its highest level against the dollar since late January. At 1355 GMT the zloty was trading at 3.7496 to the dollar.

Write to Patryk Wasilewski at patryk.wasilewski@wsj.com