* CSI -1.5pct; SSEC -1.3pct; HSI +0.3pct
* PBOC vows to stabilise financial market expectations
* July Caixin services PMI hits 11-mth high
HONG KONG, Aug 5 (Reuters) - China stocks fell on Wednesday, shrugging off a vow by the central bank to stabilise market expectations and a private survey which showed activity in the services sector activity accelerated last month.
With major benchmark indexes still down some 25 percent since mid-June, investor confidence remains shaky even after a flurry of unprecedented market support measures from Beijing in recent weeks, analysts said.
The CSI300 index fell 1.5 percent to 3,889.03 points by the end of the morning session, while the Shanghai Composite Index lost 1.3 percent to 3,708.66 points.
China CSI300 stock index futures for August fell 2.2 percent to 3,752.8, or 136.23 points below the current value of the underlying index, pointing to expectations of further weakness.
"The stock market lacks supports from economic fundamentals and fund supplies to rebound sharply for the rest of the year," said Zhang Gang, an analyst at Central China Securities in Shanghai.
A shares will likely trade between 3,300-4,200 points in the next six months, Zhang said.
While activity in China's services sector expanded at its fastest pace in 11 months in July, the composite output index which covers both factory and services activity fell to 50.2 from 50.6, barely in positive territory and reflecting a growing drag from weakness in manufacturing.
China's central bank promised to "stabilise financial market expectations" on Tuesday, saying it will head off risks in the latest show of official resolve to keep the economy on an even keel.
In Hong Kong, the Hang Seng index added 0.3 percent to 24,472.48 points.
The Hong Kong China Enterprises Index gained 0.8 percent to 11,162.05.
The index measuring price differences between dual-listed companies in Shanghai and Hong Kong stood at 137.36.
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.
The northbound quota for the Hong Kong-Shanghai Stock Connect, currently set at 13 billion yuan, saw net inflows of 0.35 billion yuan.
Total volume of A shares traded in Shanghai was 21.64 billion shares, while Shenzhen volume was 16.26 billion shares.
Total trading volume of companies included in the HSI index was 0.5 billion shares.
China stock market graphics suite reut.rs/1HcUe19
(includes timeline of crash, PE ratios, market caps)
A-share account openings spike bit.ly/1wvJ9S9
Comparison of stock indexes and selected company stocks
Chinese A-shares vs developed and emerging stocks
link.reuters.com/rac25w (Reporting by Michelle Chen; Editing by Kim Coghill)