BEIJING - The former head of China's drug administration is being investigated on suspicion of taking bribes to allow companies to get around drug approval standards, state media reported Sunday.

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Zheng Xiaoyu, removed from the post as head of the State Food and Drug Administration in June 2005, is suspected in a string of bribery cases, Xinhua News Agency said, citing the China Business Post.

Xinhua said two former department directors under Zheng, Hao Heping and Cao Wenzhuang, were also under investigation.

The Chinese government has been fighting a wave of top-level corruption cases that threaten to undermine its legitimacy. Government and party leaders have been arrested in major cities in the past year, including Shanghai's Communist Party secretary, Chen Liangyu.

Xinhua said Zheng was named director of the drug administration when it was set up in 1998 and was in charge of implementing a national standard for the approval of drugs before they are allowed to go on sale.

It said some drug companies gave bribes so that lower-quality medicines would win approval, citing the case of Xinfu, an antibiotic drug made by a company in Anhui province in eastern China that caused at least 10 deaths in the last year before it was banned.