Mainland Chinese shares were trading lower after the country's top regulator barred 24 accounts from trading on the Shanghai and Shenzhen stock exchanges.
The China Securities Regulatory Commission said the accounts were under investigation for spoofing, an illegal practice which involves placing and then immediately cancelling orders to move prices.
The benchmark Shanghai Composite index was down 1% at 3,669.44 points at mid-day, while the Shenzhen index fell by 0.4% to 2,119.23.
Markets elsewhere in the region were tentatively positive, with Hong Kong's Hang Seng adding 0.4% at 24,595.51.
In Tokyo, the Nikkei index was up by 0.1% at 20,542.39 points after official data showed inflation slowed and household spending unexpectedly tumbled in June.
The consumer price index advanced 0.4% from a year ago, down from the 0.5% increase recorded in May and well short of the central bank's 2% target.
Core inflation, which strips out volatile prices of fresh food, edged up by 0.1%.
Separately, the Ministry of Internal Affairs and Communications said household spending slumped 2% in June, belying analyst forecasts of a 1.9% rise.
Analysts say the disappointing data could persuade the Bank of Japan (BOJ) to expand its stimulus programme.
"If the BOJ were to ease this year, it will probably be in response to weakness in the economy than to inflation figures," Yoshiki Shinke, chief economist at Dai-ichi Life Research Institute, told Reuters.
"Risks to the economic outlook are clearly tilted to the downside and with consumption so weak, we may not see a clear rebound in growth in July-September as the BOJ projects."
Meanwhile, Seoul's KOSPI benchmark was broadly unchanged at 2,017.99 points.
Figures released earlier by Statistics Korea showed industrial production increased 1.2% year-on-year in June, the fastest pace of growth posted by the Mers-afflicted country in 2015.
Elsewhere, shares in Australia were up, with the S&P/ASX 200 index climbing 0.5% at 5,698.00.