SEOUL, Oct 29 (Reuters) - South Korea’s factory output in September declined from a month earlier as global chip shortages weighed on car production and output unexpectedly fell on a year-on-year basis, ending a 10th month of growth. Industrial production last month fell by a seasonally adjusted 0.8%, missing a median 0.3% decline tipped in a Reuters survey and following 0.7% drop in August. On an annual basis, output unexpectedly contracted 1.8%, missing a 1.4% growth forecast in the poll and down from a 9.7% expansion in August. Reporting by Joori Roh; Editing by Christian Schmollinger