Chinese search engine Baidu has fired four employees for accepting bribes to delete content on its online forum.

Baidu discovered the employees' "suspicious behavior" after a recent crackdown on illegal online post deletion. It then reported the activities to the authorities, which led to the arrest of the three employees. A fourth employee was stopped by the company before "any major damage" had been done, but fired for violating ethic practices.

A Baidu spokeswoman said that the content deletion occurred on the company's online forum, Baidu Tieba. Baidu does not accept any payment in handling online user complaints and monitors employees with authority to delete posts.

Illegal post deletion is a major problem for the Chinese Internet, the company said in its statement. An online industry has emerged in China offering paid services to users wanting to delete sensitive content from prominent websites. Professional post deleting companies, claim they can delete any posts from Baidu Tieba, along with other Chinese sites and do so by bribing admin workers.

One company charges US$237 to kill off posts on faulty furnaces. Baidu said the company is working with Chinese authorities to crack down on the practice of illegal content deletion.