Chinese state-sponsored hackers breached the Treasury Department's computer security guardrails this month, according to a letter to lawmakers that Treasury officials provided to Reuters.

The "threat actor" was able to access the workstations via a compromised third-party cybersecurity service provider called BeyondTrust, the department said.

The incident comes in the final days of the Biden presidency and as officials work to root out China-tied hackers from U.S. telecommunications systems.