WASHINGTON, March 3 (Reuters) - A U.S. senator berated Federal Reserve Chairman Ben Bernanke on Tuesday for refusing to name banks that borrow from the central bank, and said he would introduce legislation requiring public disclosure.

In a testy exchange at a hearing before the Senate Budget Committee, Vermont Sen. Bernie Sanders, an independent who usually votes with the Democrats, said he found it “unacceptable” that the central bank risked taxpayer money without detailing where the funds went.

“My question to you is, will you tell the American people to whom you lent $2.2 trillion of their dollars?” Sanders asked, referring to the size of the Fed’s balance sheet.

Bernanke responded that the Fed explains the various lending programs on its website, and details the terms and collateral requirements.

When Sanders pressed on whether he would name the firms that borrowed from the Fed, the central bank chairman replied, “No,” and started to say that doing so risked stigmatizing banks and discouraging them from borrowing from the central bank.

“Isn’t that too bad,” Sanders interrupted, cutting off Bernanke’s answer. “They took the money but they don’t want to be public about the fact that they received it.”

He said businesses in his state were in trouble and needed loans, but were not permitted to borrow from the Fed.

“Do you have to be a large, greedy, reckless financial institution to apply for this money?” he asked.

Bernanke said the Fed’s lending programs were not gifts or subsidies but rather over-collateralized loans. He said the law restricted the types of firms to which the central bank can lend.

“We have never lost a penny doing it,” he said.

Sanders responded: “Let me just say this, Mr. Chairman. I have a hard time understanding how you have put $2.2 trillion at risk without making those names available, those institutions public.”

“We are going to introduce legislation today, by the way, to demand that you do that. It is unacceptable to me that that this goes on,” he added. (Reporting by Emily Kaiser, Editing by Chizu Nomiyama)