* CSI300 -0.2 pct; SSEC -0.3 pct; HSI: -0.4 pct
* Shares of China carriers jump on govt pledge to open airspace
* China services sector expansion slows in April
SHANGHAI, May 5 (Reuters) - China stocks dipped on Thursday morning, with trading volume continuing to dwindle amid fresh signs that the country's nascent economic recovery is resting on weak foundations.
Hong Kong shares tracked U.S. markets lower, as worries about global economic growth resurfaced.
China's blue-chip CSI300 index fell 0.2 percent, to 3,202.33 points by the lunch break, while the Shanghai Composite Index lost 0.3 percent, to 2,983.06 points.
In Hong Kong, the Hang Seng index dropped 0.4 percent, while the Hong Kong China Enterprises Index lost 0.9 percent.
China's robust market rebound since early March appears to be losing momentum as trading volumes have shrunk and the SSEC fails to stand decisively above the 3,000 mark - seen by many as a key psychological level.
Worries are mounting that the country's debt-fuelled recovery in the first quarter could be short-lived, amid signs that fresh liquidity has failed to energise China's economic muscles, with the spill-over boosting property and commodity prices instead.
A private survey showed on Thursday that activity in China's services sector expanded in April, but the gains were slightly less robust than in March.
Most sectors in China fell, but airline stocks surged after China's central government on Wednesday unveiled plans to promote airline transportation by pledging to open up low-altitude air space.
China's biggest carriers, including Air China Ltd , China Eastern Airlines and China Southern Airlines all jumped more than 3 percent.
In Hong Kong, sentiment was soured by overnight weakness on Wall Street, where major share indexes declined in the wake of weak job and worker productivity data.
Reporting by Samuel Shen and Pete Sweeney; Editing by Jacqueline Wong