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.

According to a letter to lawmakers that Treasury officials made public on Monday, Chinese state-sponsored hackers made their way past the U.S. Treasury Department's computer security system this month, gaining access to documents in what's being called a "major incident."

China slammed the U.S. Treasury's sanctions against cybersecurity firm Integrity Technology Group for its alleged role in hacking incidents.

Ill., the top Democrat on the House select committee on China, raised concerns about the breach to Treasury Secretary Janet Yellen and asked for a meeting to discuss the situation by Jan. 15. A Treasury official told Semafor that the agency has already offered briefings to Congress.