The nation's top securities watchdog said late on Thursday that it had shut down 3,577 accounts that were involved in illegal over-the-counter margin trading activities as of Wednesday.
The China Securities Regulatory Commission (CSRC) said that it would continue to eradicate these practices in an orderly manner.
Securities companies should communicate with their clients and help them "adjust such practices, instead of simply and unilaterally terminating contracts,"said the CSRC in a post on its official Weibo account.
The CSRC also disclosed that the nation's stock accounts totaled 200 million in August, up 39.4 percent year-on-year, with a value of 43.8 trillion yuan ($6.9 trillion).
Stock markets on the Chinese mainland fell on Thursday, with the benchmark Shanghai Composite Index dropping 2.1 percent and the Shenzhen Component Index declining 1.52 percent.