Photo taken on Jan. 14, 2013 shows the headquarters of Internet firm Tencent in Shenzhen, south China's Guangdong Province. [Photo: Xinhua/Liang Xu]

Several leading websites, including Sina, Baidu and Tencent, have been told to improve internal management and close loopholes, according to the Cyberspace Administration of China (CAC) on Monday.

CAC uncovered problems concerning content management and staff training, during an inspection of eight commercial websites and news applications, said a statement from the CAC.

Regulators found serious problems in the management of QQ.com, which is operated by Tencent, and Ifeng.com, operated by Phoenix New Media. The executives of both websites have been interviewed, the statement said.

The other website and application operators have been asked to correct the problems discovered.

By the end of this year, Internet regulators will be pushing websites to improve their internal management, for instance, through the adoption of proper regulations, the statement said.