WASHINGTON: Former Federal Reserve Chairman Alan Greenspan signaled that the financial crisis has yet to end even as borrowing costs tumble, warning that US banks must raise "large" amounts of money.

"There is still a very large unfunded capital requirement in the commercial banking system in the United States and that's got to be funded," Greenspan said in an interview in Washington. He also said that "until the price of homes flattens out we still have a very serious potential mortgage crisis."

Greenspan's comments suggest he sees a bigger capital shortfall in the banking system than reflected in regulators' stress tests on the 19 biggest US lenders. Treasury Secretary Timothy Geithner told lawmakers that banks have issued more than $56 billion in new stock or debt since the tests found 10 firms needed to raise about $75 billion.