Chinese internet authorities have ordered the country's leading search engine to overhaul its operations after an investigation found its search results had misled the public.
Baidu "relied excessively on profits from paid listings in search results, and did not clearly label such listings as the result of commercial promotion," the Cyberspace Administration of China said late Monday.
As a result the "objectivity and impartiality of search results" were compromised, it said.
The probe into Baidu's paid search listings was launched last week amid a public outcry over the death of a student, Wei Zixi, who underwent experimental cancer treatment in a hospital that had appeared at the top of search results.
After treatment but before his death last month, Wei publicly accused Baidu and the Second Hospital of the Beijing Armed Police Corps of promoting false medical information.
Investigators found Baidu's search results did influence Wei's choice of medical treatment and told Baidu it had to make changes in several areas, the administration said, without providing details.
Health and commerce authorities also opened an investigation into the hospital, but results have yet to be publicised.
Baidu displays text at the end of advertised website descriptions with two characters stating that it is a promotion.
However, angry internet users say the notice is not prominent enough and preys on "ordinary people."
The investigation follows an earlier scandal in January where Baidu admitted it allows healthcare companies to pay for the right to moderate online health information forums.
Baidu enjoys a near monopoly in China, which blocks many online services Google's search engine, after Google refused to comply with Beijing's requests for it to censor politically sensitive content.