* CSI300 -2.2 pct; SSEC -2.8 pct; HSI +0.6 pct
* China share falls triggered by fears over margin calls
* Hong Kong stocks rebound, Fed meeting in focus
SHANGHAI, Jan 27 (Reuters) - China stocks tumbled again on Wednesday, hitting fresh one-year lows amid signs the recent market rout is triggering margin calls and forced liquidation, threatening yet another vicious downward market spiral.
Fresh economic data did little to aid sentiment with industrial profit falling 4.7 percent in December, the seventh straight month of declines.
Hong Kong shares rebounded, probably helped by modest improvement in other regional markets though investors remained nervous as oil pulled back again and as they waited on a policy decision from the Federal Reserve later in the day.
The CSI300 index fell 2.2 percent, to 2,875.10 points at the end of the morning session, while the Shanghai Composite Index lost 2.8 percent, to 2,672.45 points.
Hong Kong's Hang Seng index added 0.6 percent, to 18,967.31 points, while the Hong Kong China Enterprises Index gained 0.2 percent, to 7,908.96.
The index measuring price differences between dual-listed companies in Shanghai and Hong Kong stood at 137.29.
A value above 100 indicates Shanghai shares are pricing at a premium to shares in the same company trading in Hong Kong, and vice versa.
Samuel Shen and Pete Sweeney; Editing by Shri Navaratnam