Four employees, including the three who were arrested, were fired after the company found suspicious deletions of posts on its Baidu Postbar forum in July.
Three of them were reported to the police and subsequently arrested due to large sums of money involved, said Betty Tian, a Baidu spokeswoman.
Baidu did not provide information on who had asked for the deletions or the nature of the posts that were deleted from the forum, where users can discuss a wide range of topics.
"During the company's recent crackdown on illegal online post deletion activities, Baidu has discovered suspicious behavior with several of its employees," the company said in a statement.
China's freewheeling Internet scene, with over half a billion users, has struggled to keep poor business practices at bay as it expands at a rapid clip.
Alibaba Group said in July that a former general manager of its group deals website had been detained by police for allegedly accepting bribes.
In February 2011, the chief executive and chief operating officer of Alibaba Group's business-to-business website, Alibaba.com, resigned after a spike in fraudulent transactions on the platform.
Copyright Thomson Reuters 2012
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