BEIJING -(Dow Jones)- China's information industry regulator has asked government offices, companies and other organizations involved in the business or oversight of Internet addresses to submit plans by the end of the month detailing their efforts protect the domain name system, in another sign of Beijing's tightening control over the Internet.

China must strengthen the security of its domain name system and step up efforts to combat "external network attacks, domain name hijacking and other threats," according to a directive dated Jan. 30 but posted Monday on the Web site of the Ministry of Industry and Information Technology.

A domain name is a means of identifying a location on the World Wide Web.

The directive, which has a deadline of Feb. 28, was issued to government telecommunications bureaus, the country's three big state-controlled telecommunications firms--China Mobile Communications Corp., China Telecommunications Corp. and China Unicom Group--as well organizations involved in telecommunications research and domain name registration services in China.

China has been tightening its control over the Internet, especially after the discovery of a series of cyber attacks that appear to have originated in the country and as U.S. Internet giant Google Inc. (GOOG) is considering whether to pull out of China, partly because of Internet security issues.

In December, the China Internet Network Information Center, known as CNNIC, a semi-official office that administers China's domain names, said all new registrants of domain-names with China's ".cn" suffix are required to show proof they are a government-registered business or organization, effectively making it harder for individuals to set up domestic Web sites.

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