But China has used its antimonopoly law, which went into effect in 2008, with a special zeal against United States technology companies.

Last week, the state media announced that a separate regulatory body, the National Development and Reform Commission, was looking into possible antitrust violations by Qualcomm, one of the world’s largest makers of the chips used in mobile devices. According to the Securities Times newspaper, the agency is investigating accusations that the company overcharged Chinese customers and abused its dominant market position.

Whether intentional or not, the announcement coincided with a visit to China last week by Qualcomm’s chief executive, Steven M. Mollenkopf, who held talks with government officials and announced the creation of a $150 million “strategic venture fund” to invest in Chinese technology start-up companies.

In May, Bloomberg reported that the Chinese government has started to examine the dependence of Chinese banks on computer servers made by IBM.

In April, the United States Chamber of Commerce sent a letter to Secretary of State John Kerry and Treasury Secretary Jacob J. Lew expressing concern that Chinese authorities were using their antimonopoly law “to advance industrial policies that nurture domestic enterprises, rather than the internationally accepted norm of using competition law to protect consumer welfare and competition.”

Meanwhile, Chinese news media reports have named Microsoft as among the foreign technology companies likely to come under tighter government checks for security risks after the revelations by Edward J. Snowden about United States government surveillance.

“It’s a combination of punishment and paranoia,” said James Lewis, a cybersecurity expert at the Center for Strategic and International Studies, a research group. “The Chinese government has always been suspicious of U.S. I.T. products and is using Snowden as an excuse.”