Former Federal Reserve Chair Janet Yellen criticized the federal investigation into the central bank and its chairman Jerome Powell on Monday, calling it "extremely chilling."

The former US Treasury Secretary during the administration of former President Joe Biden warned of the persecution policy implemented by the Trump administration.

“I'm surprised the market isn't more concerned. I think it should be,” said Yellen, who chaired the Fed from 2014 to 2018, in an interview with CNBC.

Powell announced this Sunday that he faces a federal investigation related to his testimony before Congress last June about the multibillion-dollar renovation of the central bank's headquarters.

“On Friday, the Justice Department served the Federal Reserve (Fed) with grand jury subpoenas, threatening a criminal indictment related to my testimony before the Senate Banking Committee last June,” the Fed chair said in a statement and video.

According to Powell, the testimony referred in part to a multi-year project to renovate the Fed's historic office buildings.

Yellen pointed out that, “knowing Powell as well as I do, the odds that he lied are zero, so I think they're going after him because they want his job and they I want him gone.”

Yellen, along with other former Fed officials, also condemned the federal investigation against Powell in a statement, asserting that the institution's independence is “crucial to economic performance.”

“The alleged criminal investigation against Federal Reserve Chairman Jay Powell,”This constitutes an unprecedented attempt. to use fiscal attacks to undermine that independence," the signatories stated.