BEIJING >> Two corporate investigators, a Briton and an American, have been arrested in Shanghai on charges of illegally selling personal information about Chinese citizens, police announced Tuesday.

The announcement was the Chinese government’s first word on Peter Humphrey and Yingzeng Yu, a married couple who operate ChinaWhys Ltd., an investigation firm in Shanghai that serves corporate clients. They were detained in July.

The communist Beijing government operates an extensive surveillance network to track China’s public but is tightening controls on access to personal information by companies and individuals.

Communist leaders were embarrassed last year by news reports that disclosed details of the family wealth of Xi Jinping, the new ruling party leader, and retiring Premier Wen Jiabao.

Earlier, several Chinese companies complained about investigations into their operations that led to a fall in their share prices on foreign stock exchanges.

Several dozen reports prepared by Humphrey and Yu contained information that “seriously violated the legitimate rights of citizens,” the Shanghai police department said in a statement. It said they were formally arrested on Aug. 16.

That included home addresses and information on family members, real estate and vehicles, the statement said. It said they were sold to clients including manufacturers, law firms and financial institutions.

The British Embassy in Beijing confirmed last week that Humphrey was arrested but gave no details of charges. The embassy said it was providing unspecified consular assistance to his family.

The detentions coincided with the announcement in July of an investigation into possible bribery of doctors by employees of pharmaceutical company GlaxoSmithKline. That prompted suggestions their case might be linked to Glaxo, but Tuesday’s announcement made no mention of that.

Tuesday’s announcement said Shanghai police are investigating 126 people on suspicion of improperly gathering personal information and have detained 35.

ChinaWhys says its services include screening potential employees or business partners.

It is one of a number of such firms in China that serve foreign and local companies that want to protect themselves against fraud, embezzlement or misconduct by employees or business partners.

Humphrey, a former reporter for the Reuters news agency, has worked as an investigator for the past 14 years in Asia, focusing on white-collar crime prevention, fraud investigation and crisis mitigation, according to the ChinaWhys website.

Yu has worked for or advised companies in the United States, Hong Kong and China in technology, medical products and other industries over a 25-year business career, according to the company.

In January, a court in Shanghai sentenced four former executives of a unit of Dun & Bradstreet Corp. to up to two years in prison on charges of illegally buying information about Chinese consumers. The company was fined 1 million yuan ($160,000).