* SSEC -0.1 pct, CSI300 0.0 pct, HSI -0.5 pct
* China April service sector growth slowest in nearly a year
* Small-caps bounce strongly
SHANGHAI, May 4 (Reuters) - China stocks were flat at midday on Thursday, as strong gains in small-caps offset a survey showing softer services sector activity which raised concerns over growing economic risks.
The CSI300 index was unchanged at 3,412.49 points at the end of the morning session, while the Shanghai Composite Index lost 0.1 percent, to 3,133.21 points.
Growth in China's services sector cooled to its slowest in almost a year in April as fears of slower economic growth dented business confidence, even as cost pressures eased, a private survey showed on Thursday.
The findings echoed a similar trend of slowing growth seen in China's official factory and services surveys on Sunday.
"A turning point in growth appeared to have emerged at the beginning of the second quarter. Investors should be cautious about downward risks in the economy," Zhengsheng Zhong, Director of Macroeconomic Analysis at CEBM Group said in a note.
Further curbing sentiment, the securities regulator on Wednesday vowed to step up efforts to prevent and control financial risks ahead of a key Party Congress later this year.
Participants had already been rattled by tougher regulations recently to dampen market speculation, but Liu Qihao, an analyst with Shanghai Securities, said chances for a major downturn in the main indexes were low.
Sector performance was mixed in the morning session.
Small-caps outperformed the broader market, with the tech-heavy start-up board ChiNext rallying 0.8 percent.
Stocks expected to benefit from the planned Xiongan New Economic Zone, an area modelled on the Shenzhen special economic zone, also bounced strongly, with more than 10 of those stocks surging 10 percent.
"In the long run, the building of Xiongan Area would certainly help lift the results of those related listed companies, but for now it's mainly short-term speculation," said Liu.
Losses were seen in material and energy stocks, dragged down by an across-the-board sell-off in the commodities market.
In Hong Kong, stocks retreated after the Federal Reserve delivered a hawkish policy statement.
The Fed kept its benchmark interest rate steady as expected, but downplayed weak first-quarter economic growth and emphasised the strength of the labour market, a sign it was still on track for two more rate increases this year.
The Hang Seng index dropped 0.5 percent, to 24,565.64 points.
The Hong Kong China Enterprises Index lost 1.0 percent, to 10,073.66.
Reporting by Luoyan Liu and John Ruwitch; Editing by Jacqueline Wong