China's internet search giant Baidu was recently accused by the state media of allowing unlicensed medical services to buy high search rankings and now Baidu has pledged to overhaul its operations.

The market in the world's largest internet population is dominated by the search engine, with nearly 60% of users; quite ahead of Google, which leads the field internationally.

However, the recent episode has led to a fall in Baidu's stock and users complain about the way the Nasdaq-listed firm allows companies to buy their way up the list of search results. Yesterday, Robin Li, Baidu's chief executive officer informed that the firm had sacked some staff over the case and could fire more. He added, "We have already fired people who helped fabricate documents for unlicensed suppliers."

He also said, "We have removed the keywords of all four clients mentioned in the report and have begun to double-check the licences of all other hospitals and pharmacies on our client list." Through a statement, Baidu informed that paid search listings for those companies had been removed, which had not filed details of their licences pending checks. The statement also said that those customers together accounted for around 10-15% of its total revenues.