* CSI -2.3 pct, SSEC -1.9 pct
* HSI +0.1 pct, HSCE -1.0 pct
* CSI300 futures slide for 3rd day
* Hong Kong market shuts, to reopen Monday
SHANGHAI, Dec 24 (Reuters) - China stock indexes fell on Wednesday, with signs emerging in futures contracts that what analysts originally saw as a profit-taking blip earlier in the week for mainland stocks may be gaining traction.
The Hong Kong market, which closed at midday Wednesday and won't reopen until Monday, edged up.
China CSI300 stock index futures for January fell 3.3 percent, to 3,257, a spread of 9.9 points above the current value of the underlying index, the third straight day of declines. All other futures contracts for that index declined by similar margins.
The CSI300 index fell 2.3 percent, to 3,247.14 points at the end of the morning session, while the Shanghai Composite Index lost 1.9 percent, to 2,975.64 points, dropping below 3,000 - considered a sentiment support level - for the first time since Dec. 17.
Analysts were divided as to the reason for the retreat, with some pointing to nervousness over signs regulators are cracking down on excessive margin financing and pricing manipulation as the cause for the stall.
However, diminished anticipation for future monetary easing was also to blame, according to Xiao Shijun, an analyst at Guodu Securities in Beijing.
"The interest rate cut has proved to be not very effective in lifting the slowing economy so far, so the long-awaited cut of bank reserve requirement ratios is seen as much less likely," he said.
That, Xiao said, "dampens the investors' confidence on the sustainability of the current bull run."
The Hang Seng index added 0.1 percent, to close at 23,349.34 points. Hong Kong markets closed at midday Wednesday and will not reopen until Monday, Dec. 29.
The Hong Kong China Enterprises Index lost 1.0 percent, to 11,558.02.
"The market is slow and quiet, investors are heading for holidays," said Alfred Chan, chief dealer at Cheer Pearl Investment In Hong Kong.
The index measuring price differences between dual-listed companies in Shanghai and Hong Kong shrank slightly to stand at 118.53.
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.
Total volume of A shares traded in Shanghai was 21.81 billion shares, while Shenzhen volume was 8.87 billion shares.
Total trading volume of companies included in the HSI index was 0.7 billion shares. (Reporting by Pete Sweeney, Chen Yixin and the Shanghai Newsroom; Editing by Richard Borsuk)