An actor affiliated with the Chinese government it was recently hacked US Treasury officials on Monday announced a “major event”.

In a letter obtained by FOX Business Treasury Department He disclosed the incident to the leadership of the Banking Committee of the Senate. Officials learned about the breach on December 8.

A cybercriminal reportedly gained access to Treasury Department workstations and documents via a security key.

“After the Treasury was alerted by the service provider, we immediately contacted the Cyber ​​Security and Infrastructure Security Agency (CISA) and worked with law enforcement partners across government to determine the impact of this incident,” the spokesperson said.

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The US Treasury Building is pictured on Friday, July 16, 2021, in Washington, DC. (via Kent Nishimura/Los Angeles Times, Getty Images/Getty Images)

“The service that compromised BeyondTrust has been taken offline and there is no evidence that the threat actor continues to have access to Treasury systems or data.”

The news comes as state-run Chinese hackers continue their espionage campaign against the US government. last week, The White House said Chinese officials have accessed the private texts and phone calls of Americans, targeting a US telecommunications company — the ninth telecommunications company affected by a Chinese hacking attack.

Speaking to reporters, Deputy National Security Adviser Anne Neuberger said the government plans additional measures in the coming weeks in response to the hacking campaign, but did not provide specific details.

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The Treasury Department building is seen on August 29, 2022 in Washington, DC. ((Photo by DANIEL SLIM/AFP via Getty Images) / Getty Images)

The number of Americans affected by the latest telecom attack is unknown because Chinese hackers are careful to cover their tracks, Neuberger said. Most of the victims were located in Washington, DC and Virginia.

“We believe this is to determine who those phones belong to and whether they are a target of government interest and whether the communications, texts and phone calls on those phones constitute further espionage and intelligence gathering,” he said.

“Salt Typhoon”, which US officials call the Chinese government's espionage unit, has been active for the past 4 years. It is not known whether the latest Treasury incident is related to Salt Typhoon or another CCP-affiliated actor.

Chinese President Xi Jinping applauds during a joint press conference of the China-Central Asia Summit in Xi'an, north China's Shaanxi Province, May 19, 2023. (Photo by FLORENCE LO/POOL/AFP via Getty Images/Getty Images)

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FOX Business reached out to the Treasury Department for additional information, but did not immediately receive a response.

FOX Business' Landon Mion contributed to this report.