South Korean stocks started lower Thursday as investors sat on the sidelines ahead of a key decision by the U.S. central bank, analysts said.

The benchmark Korea Composite Stock Price Index (KOSPI) lost 9.96 points, or 0.51 percent, to 1,940.07 in the first 15 minutes of trading.

Most shares traded bearish, with top shipyard Hyundai Heavy Industries falling 0.61 percent and steelmaker POSCO sliding 0.95 percent.

However, tech giant Samsung Electronics gained 0.31 percent after U.S. smartphone maker Apple revealed its latest iPhone 5 handset.

The U.S. Federal Reserve will wrap up its two-day meeting on Thursday and is expected to announce a fresh round of quantitative easing.

The local currency was trading at 1,127.35 won to the U.S. dollar as of 9:15 a.m., down 0.95 won from Wednesday's close. (Yonhap News)