China's cyberspace regulator, which has recently been assigned to police future overseas listings of Chinese companies, is planning to implement new IPO rules for local entities that collect data from more than 1 million users.

The Cyberspace Administration of China posted the new rules on its website Monday. The agency said all companies that want to list abroad - namely those with data for more than 1 million users - must undergo a comprehensive security review before being allowed to proceed with the transaction.

Analysts said the new rules are meant to better protect user data privacy and to push companies to list domestically. The CAC proposed two new sets of rules under the Data Security Law and the Personal Information Protection Law. The rules are set to go into effect this year.

Under the new rules, Chinese companies that wish to list abroad must first submit all their IPO materials to the CAC. This will then be followed by a security review. The CAC is currently seeking public opinion on the proposed rules.  

The CAC said the review will focus on a company's operations, particularly the possible "risk of supply chain interruption due to political, diplomatic, trade and other factors." It will also assess the risk of key data that can be "maliciously used by foreign governments after listing in foreign countries."

The new rules are part of the CAC's latest efforts to rein in the country's rapidly growing "platform economy." It is also part of China's wider efforts to keep the power of the country's largest technology conglomerates in check.

On Sunday, the State Administration of Market Regulation said it will be blocking Tencent's plan to merge the two of China's largest videogame streaming websites - Huya and DouYu. The agency cited antitrust concerns as the reason for the move.

Tencent initially announced the merger plan last year to streamline its stakes in both companies. Analysts said both companies hold a combined 80% stake in the videogame streaming market estimated to be worth more than $3 billion.

Tencent holds a 36.9% stake in Huya and about a third of DouYu. The stakes are estimated to be worth a combined $5.3 billion.

"If Huya and DouYu are to merge, the original joint control of Douyu will become Tencent's complete control of a merged entity. Considering factors such as revenue, active users, live streaming resources and other key indices, we can expect that a merger would eliminate or restrict fair competition," the SAMR said.