The producer price index for December fell 2.0 percent from a year earlier, Bank of Korea data showed, marking the sharpest annual decline since a 2.6 percent slump in May 2013. It was also a fifth consecutive month of decline.

Leading the price drop were coal and oil products, which together dove 28.8 percent in December from a year earlier due to a global selloff in commodities amid a supply glut.

Last week, the Bank of Korea held its policy interest rate steady, in line with expectations, and slashed this year's inflation forecast by half a percentage point on the recent plunges in commodities prices.

(Reporting by Joonhee Yu; Editing by Choonsik Yoo)