(Corrects to clarify that employees of public relations companies are also being investigated, paragraphs 1, 5)
BEIJING, Sept 4 (Reuters) - Police in Shanghai are investigating eight people, including employees of the 21st Century Business Herald newspaper, on suspicion of extortion, China's official Xinhua news agency said on Thursday.
Experts have long pointed to corruption within the ranks of Chinese media, arguing that blackmail is widespread and journalists are susceptible to bribery.
China has cracked down on official corruption and extravagance since President Xi Jinping's appointment last year. Public flaunting of personal, and often illicit, wealth had been common, provoking wide criticism of the ruling Communist Party.
Police have taken "criminal coercive measures against the eight suspects" in line with the law, Xinhua's website, Xinhuanet, cited the Shanghai Public Security Bureau as saying.
The eight suspects include people working at two public relations firms, Xinhua said. It did not give their full names.
An official at the Shanghai office of the 21st Century Business Herald declined to comment. The newspaper is widely considered an influential business daily but it is not run by the government.
Xinhua said the editor-in-chief of the paper's website, surnamed Liu, its deputy editor, surnamed Zhou, and other editorial and operations staff had colluded with two financial public relations firms in Shanghai and the southern city of Shenzhen to target firms that were about to be listed or restructured to "carry out illegal activities".
Citing the police investigation that started last year, Xinhua said: "After accepting high fees from the businesses who were willing to engage in 'positive propaganda', the suspects would exaggerate positive facts or conceal negative issues."
If companies did not cooperate, the newspaper would "release negative reports maliciously attacking them" and "blackmail" them into signing advertising or cooperation deals, Xinhua said.
Although all Chinese media are controlled by arms of the state, many news outfits such as the 21st Century Business Herald are subject to commercial pressures.
The news comes nearly a month after prosecutors detained a top Chinese news anchor for China Central Television (CCTV). In June, China's top prosecutor said it was investigating a senior executive with CCTV on suspicion of bribery. (Reporting by Sui-Lee Wee Additional reporting by Beijing Newsroom; Editing by Clarence Fernandez)