South Korea's consumer inflation eased for a fourth consecutive month in May to the lowest in 19 months but core inflation remained elevated, clouding views on whether the central bank may start to cut interest rates soon to boost economic growth. The consumer price index (CPI) rose 3.3% in May year-on-year, Statistics Korea data showed on Friday, in line with the forecast in a Reuters analysts survey and slowing from a 3.7% rise in the previous month.