China is tightening its crackdown on overseas brokerages illegally providing services to onshore investors, with regulators aiming to eradicate such activities within two years while moving to penalize three major offshore brokerages for illegal cross-border securities business activities.

The China Securities Regulatory Commission said on Friday that eight government departments, including the CSRC, the Ministry of Industry and Information Technology, the Ministry of Public Security, and the People's Bank of China, had jointly issued an implementation plan to comprehensively tackle illegal cross-border securities, futures, and fund business activities.

The plan, aimed at better protecting investors' rights and maintaining market order, seeks to "resolutely eradicate illegal activities while clearing existing business in a smooth manner" through a two-year campaign, the CSRC said.

Under the plan, overseas institutions will be prohibited from conducting marketing and client solicitation activities, providing account opening, trade execution and fund transfer services related to securities, futures, and fund businesses in the Chinese mainland. Domestic entities are also banned from assisting such illegal operations.