China said Wednesday it will more strictly enforce rules that prohibit unauthorized foreign investors from providing value-added telecommunications services, such as text messages.

Some unapproved foreign investors illegally use licenses granted to local companies to provide such services in China, the Ministry of Information Industry said on its Web site.

In the notice, MII said it aims "to strengthen management of the provision of value-added services by foreign investors and to maintain a fair market environment."

The latest notice comes as China tries to regulate the value-added service sector, which offers services like text messages and music ringtones. Efforts to regulate the sector could also boost demand for third-generation mobile phone services in future, when China issues 3G licenses.

The ministry said local regulators have until Nov. 1 to investigate and report such illegal activity to the ministry.

Value-added service providers who disregard deadlines for complying with the rules can have their license revoked, said the ministry.

It didn't name foreign investors or local value-added service providers who it said had broken the rules.

The telecommunications value-added sector includes listed companies like Tom Online and Kongzhong Corp., which are both based in Beijing. It isn't clear how MII's latest push will affect these companies.