* SSEC -0.6 pct, CSI300 -0.5 pct, HSI 0.1 pct
* Trading thin in China ahead of Mid-Autumn Festival
* Investors await policy cues from Fed meeting next week
SHANGHAI, Sept 14 (Reuters) - China stocks fell modestly in thin trading on Wednesday, with many traders already heading out of the office ahead of a long holiday weekend.
Hong Kong stocks were little changed as traders refused to make big directional bets ahead of next week's Federal Reserve policy meeting.
China's blue-chip CSI300 index fell 0.5 percent to 3,243.37 points by the lunch break, while the Shanghai Composite Index lost 0.6 percent to 3,005.80 points.
China's upbeat August economic data released on Tuesday, which showed both factory output and retail sales grew faster than expected, has failed to inject vigour into the market during the shortened trading week.
"Trading is typically light ahead of holidays," Chang Chengwei, analyst at brokerage Hengtai Futures said, noting that the mid-Autumn Festival on Thursday and Friday will soon be followed by China's National Day holiday which starts on Oct. 1, curbing risk appetite.
"August data failed to excite the market because many believe the recovery was the result of government stimulus, and is not sustainable."
Most sectors fell in China, with transportation and raw material stocks leading the decline.
Hong Kong stocks were little changed, with overnight losses on Wall Street dampening sentiment. The city's financial markets will be open on Thursday but will be closed on Friday.
The Hang Seng index edged up 0.1 percent to 23,234.38 points, while the Hong Kong China Enterprises Index dipped 0.1 percent to 9,560.41.
All eyes are on the Federal Open Market Committee (FOMC) meeting on Sept. 20-21 as traders anxiously wait for clues on whether the Fed will raise interest rates soon. Few traders expect a rate hike next week and markets are pricing in only a roughly 50-50 chance of one in December.
Reporting by Samuel Shen and John Ruwitch; Editing by Kim Coghill