Securities regulators announce curbs on intraday short-sellers in a move aimed at further stabilizing the world's second-largest equity market.

Investors who sell borrowed shares must wait one day to pay back their positions, according to statements from the Shanghai and Shenzhen stock exchanges issued on Monday night.

The regulatory move, which comes into effect immediately, prevents investors from selling and buying back stocks on the same day, a practice that may "amplify abnormal fluctuation in stock prices and affect market stability," said the Shenzhen bourse on its official microblog.

China already bans investors who buy shares from selling them until the next day and now such intraday trading restrictions have been expanded to short sellers.

The adoption of the T+1 rule for short selling won't affect normal margin trading and securities financing and will help strengthen market stability, added the exchange.

Securities watchdogs have unveiled a string of policies to shore up the market, as the benchmark Shanghai index lost 30 percent from its June 12 peak, which included suspending initial public offerings, banning major shareholders from selling, investigating into "malicious short-selling" and granting government agency liquidity to help finance stock purchases.

The exchanges have frozen 38 trading accounts, including one owned by hedge fund magnet Citadel Securities LLC, according to Bloomberg, as algorithmic trading turns into authorities' attention who seek causes behind market volatility.

The Shanghai Composite Index closed at 3622.91 on Monday, down 1.1 percent.

Bloomberg contributed to this story.