Former U.S. Federal Reserve Chairman Alan Greenspan said on Friday that U.S bank lending will not return to normal without a big injection of public or private capital.

"The restoration of normal bank lending by U.S. banks will require a very large capital infusion from private or public sources," Greenspan said in a conference at the Mexican resort of Acapulco.

Bloomberg reports that Greenspan estimated that banks will need “north of $750 billion” in fresh capital. While some of that may be raised by increased bank cash flows, he said a “deep hole” remains.