(Bloomberg) -- Beijing curtailed access by overseas firms to Chinese data sources at least in part because of a series of reports written by US research institutions that alarmed officials, the Wall Street Journal reported, citing people with knowledge of the matter.

Senior officials grew concerned about research by American think-tanks based on public local data sources that focused on sensitive issues such as collaboration between the military and private organizations, the Journal reported. Those reports emanated from sources such as the Center for Security and Emerging Technology at Georgetown University and the Center for a New American Security, which was co-founded Kurt Campbell, who is now the White House’s Indo-Pacific coordinator, the newspaper said.

Beijing is moving to tighten its grip on sensitive data as tensions with Washington mount. Despite the administration’s push to encourage investment into China this year, investors continue to grapple with a lack of transparency and information across swaths of the world’s No. 2 economy. 

Think-tanks, research houses and consultancies seeking information on the world’s No. 2 economy have long relied on domestic sources to dive deeper into specific issues and industries. But Chinese services such as Wind Information Co. in recent months stopped providing detailed data on the nation’s companies to overseas clients. 

That coincided with a clampdown on foreign firms that regularly gather information on businesses in the country. Consultancies are under the microscope in particular, with Beijing in recent weeks targeting the local offices of Bain & Co., Mintz Group and Capvision, according to media reports. And the government just last month passed a counter-espionage law that expanded the list of activities that could be considered spying.

“By taking crucial data off the table, public discourse on China will drift further from the truth. It’s a reckless move by China to limit access to the data,” said Dakota Cary, a China-focused consultant at Krebs Stamos Group who previously worked for CSET at Georgetown. “The US-China relationship will be made worse by this decision.”

Read more: China Restricts Overseas Access to Key Corporate Information

The Cyberspace Administration of China, the country’s powerful internet overseer, notified data providers in March to restrict overseas access to sensitive information such as patents and statistics, the Journal reported, citing people who have consulted with Chinese authorities. Organizations received notices in March warning about upcoming restrictions on services including the popular academic database China National Knowledge Infrastructure, the University of California, Berkeley said in an online notice.

“Many content types that were previously viewed as mundane have now been flagged by the Chinese authorities to be subject to government review,” the university’s library said in its notice. “The duration of such suspensions is not yet known, but we have been told that access will resume upon CAC determining that Chinese publishers have addressed their requirements for the review of the affected content types.”

One report in particular that caught Beijing’s eye was a policy brief published by CSET in June, titled “Silicon Twist,” according to the Journal. That report focused on the military’s access to American-designed chips intended to train artificial intelligence models. The authors said they analyzed thousands of purchasing records to formulate their conclusions, and described steps the US government could take to cut off that access.

Another, from the same center, zeroed in on how Beijing employed programs to track and recruit talent from around the globe to boost its strategic goals, the Journal reported. The think-tank had relied on sources including China National Knowledge Infrastructure, said Lynne Weil, a spokeswoman for the institution. But she said it had no insight into what may have triggered information curbs.

Read more: Foreign Executives in China Ask ‘Who’s Next?’ After Bain Probe

Representatives for the Center for a New American Security weren’t immediately available for comment outside regular business hours.

Chinese data has gradually become less available, Hao Hong, chief economist at Grow Investment Group, told Bloomberg Television on Monday. 

“People learn to get around the issue by using different data sources, but at the end of the day it’s becoming harder to analyze what’s going on in China,” he said.

--With assistance from Rebecca Choong Wilkins.

(Updates with analysts’ comments from the sixth paragraph)

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