* CSI300 -0.9 pct; SSEC -0.8 pct; HSI: +0.2 pct
* Many investors on sidelines, British vote on EU to close to call
* China steelmakers fall as EU may consider new trade sanctions
SHANGHAI, June 23 (Reuters) - China stocks fell nearly 1 percent on Thursday, while Hong Kong shares were little changed, as investors braced for Britain's vote on whether to leave the European Union.
China's blue-chip CSI300 index fell 0.9 percent to 3,105.81 points by the lunch break, while the Shanghai Composite Index lost 0.8 percent to 2,881.55 points.
In Hong Kong, the Hang Seng index added 0.2 percent, but the Hong Kong China Enterprises Index lost 0.1 percent.
Trading was thin in both markets as investors took to the sidelines awaiting Thursday's referendum. Results will begin emerging early on Friday morning in Asia, with most expected between 0100 and 0300 GMT.
Most opinion polls put the "Leave" and "Remain" camps neck-and-neck.
Apart from roiling global financial markets, some analysts believe a Brexit could tip the UK, Europe and possibly the global economy into recession.
All main sectors were down in China.
Resources stocks lead the decline. The European Commission said on Wednesday that China's failure to curb its steel output could prompt the EU to consider new trade sanctions against Beijing.
In Hong Kong, gains in financial and service sectors offset losses in energy and IT shares.
Reporting by Samuel Shen and Nathaniel Taplin; Editing by Kim Coghill