The country's industrial output fell by a seasonally adjusted 3.5% in October from a month earlier, accelerating from a revised 1.9% decline in September, according to Statistics Korea.
It missed economists' expectations of a 1.0% fall tipped in a Reuters survey and marked the fastest decline since May 2020.
By product, cars and machineries fell 7.3% and 7.9%, respectively, leading the losses.
Output for the services sector fell 0.8%, faster than 0.2% a month before and the fastest since Dec. 2020, while retail sales lost 0.2%.
The country's factory output fell 1.1% on a yearly basis, also below 0.0% expected in the survey, snapping a 12-month streak of annual gains.
(Reporting by Jihoon Lee; Editing by Mark Porter and Muralikumar Anantharaman)
