Retail sales sank 4 percent on-month in December, turning around from a 5.7 percent on-month gain in the previous month, with a 2.2 percent on-year rise.

For all industries, production gained 0.2 percent on-month in December, following a 1.3 percent on-month rise in the previous month, with a 0.7 percent on-year fall, the data showed.

The statistics office said a downturn in car production and machinery equipment contributed to the decrease in the December figures.

Production of vehicles dropped 11.4 percent last month from a month earlier, and the machinery sector saw its output sink 4 percent.

Corporate investment continued to rise, soaring 8.9 percent on-month, as investment for machinery and transportation equipment climbed 10 percent and 4.8 percent, respectively.

However, private consumption remained weak as car purchases were delayed due to strikes at automakers.

"The output increased on the back of a rise in the service sector, as the retail sales have been in a slump, but the overall economic recovery is still being maintained," said Eo Woon-sun, director of the industrial statistics division at Statistics Korea.

For all of 2017, meanwhile, industrial output rose 2.4 percent on-year.

Its average factory operation rate lost 0.7 percentage point to 71.9 percent, the lowest level since 1998 in the aftermath of the Asian financial crisis.

Retail sales rose 2.7 percent on-year, and facility investment vaulted 14.1 percent last year. (Yonhap)