The US Federal Reserve Chair Janet Yellen on Wednesday defended the central bank's independence against some lawmakers' criticism.

In Yellen's semi-annual testimony to the House Financial Services Committee Wednesday, some lawmakers criticized her meetings with White House officials, in particular with Treasury Secretary Jacob Lew, and questioned that the Fed's independence is unduly influenced by the executive branch.

The Fed chair insisted that "Federal Reserve is independent," saying that her meetings with the White House officials did not involve discussions on monetary policy or actions the Fed is going to take.

"It is obviously critically important that the Federal Reserve be accountable to Congress. We are accountable to Congress," said Yellen.

In her testimony Tuesday to the Senate Banking Committee, Yellen also defended the central bank's independence, and expressed her strong opposition to the "Audit the Fed" bill.

Some Republican lawmakers are proposing to allow congressional audits of the Fed's monetary policy. Yellen argued that "Audit the Fed" is a bill that would politicize monetary policy and would bring short-term political pressures to bear on the Fed.