Investing.com -- Tiger Brokers will prevent China-based investors from adding to their positions starting June 12 when they are physically located on the Chinese mainland, the Singapore-based trading firm announced Tuesday.

The move follows China's directive to Tiger and competing online brokers Futu and Longbridge to close accounts that regulators have declared illegal under stricter regulations introduced on May 27.

Tiger's announcement represents one of the first tangible actions by brokerage firms to align with Beijing's updated rules.

According to Tiger's notice, investors will retain the ability to buy or sell securities from existing accounts when traveling outside mainland China.

Futu's chief executive stated during an earnings call last week that mainland investors would face restrictions on making new deposits or buying new securities, though no implementation date was provided.

Futu has ceased opening new accounts for mainland Chinese identity holders. Mainland investors represented 13% of its customer base at the end of the first quarter.

The Chinese regulator granted the firms a two-year grace period last month to wind down operations deemed illegal.