Rupert Murdoch-owned media conglomerate NewsCorp was hit with a cyberattack, and a leading cybersecurity firm, Mandient, brought in to investigate concluded the activity was likely from China, NewsCorp said Friday.

In an email to all NewsCorp employees, David Kline, NewsCorp’s chief technology officer and Billy O’Brien, its chief information security officer, said “attack activity” was discovered Jan. 20 on a system used by several of the company’s business units.

They said they believe the activity affected a “limited number of business email accounts and documents from NewsCorp headquarters, News Technology Services, Dow Jones, News UK, and New York Post.”

The company said the threat, however, is contained and “the systems housing customer and financial data were not affected. In addition, we have not experienced related interruptions to our business operations.”

They said they have also notified federal authorities.

NewsCorp said that some data was taken by a foreign government. Mandient is alleging China is involved.

“Mandiant assesses that those behind this activity have a China nexus, and we believe they are likely involved in espionage activities to collect intelligence to benefit China’s interests,” said Dave Wong, vice president, incident response at Mandiant.

NewsCorp said its “highest concern” is the protection of journalists and their sources.

A person familiar with the situation said journalists were among the targets of the alleged attack.

“We will not tolerate attacks on our journalism, nor will we be deterred from our reporting, which provides readers everywhere with the news that matters. We believe it is important that other media organizations be made aware of this threat in order to take appropriate precautions, and we are providing technical details of the attack to the Media Information Sharing and Analysis Organization,” Kline and O’Brien wrote to employees.

FBI Director Christopher Wray warned this week of the dangers of China stealing U.S. innovation — a topic he has continued to beat the drum on since becoming the agency’s director.

“The Chinese government steals staggering volumes of information and causes deep, job-destroying damage across a wide range of industries—so much so that, as you heard, we’re constantly opening new cases to counter their intelligence operations, about every 12 hours or so,” Wray said in a speech at the Ronald Reagan Presidential Library on Monday.

“Here in the U.S., they unleash a massive, sophisticated hacking program that is bigger than those of every other major nation combined,” he said without directly speaking about the NewsCorp hack. “Operating from pretty much every major city in China, with a lot of funding and sophisticated tools, and often joining forces with cyber criminals, in effect, cyber mercenaries. In just one case, one example, a group of MSS-associated criminal hackers stole terabytes of data from hundreds of companies.”