Former GOP presidential candidate Ron Paul told CNBC on Monday that his son, Sen. Rand Paul, is threatening Janet Yellen's nomination as Federal Reserve chair for only one reason: to pass the bill on more transparency for the Fed.
"He wants to hold up the appointment on her, but it's mainly to get more transparency and have the 'Audit the Fed' bill pass," Paul said.
Even though the public knows "a little bit more" about the Fed now, he said, a lot is still undisclosed, especially on the central bank's international activities.
(Read more: Sen. Paul threatens to hold Yellen nomination: Source)
"We don't know the details of the trillions of dollars that were used to bail out banks and central banks around the world and corporations during the crisis," Paul said. "The numbers that they give you I don't think are all that revealing."
Paul said that he has not discussed this matter with his son and learned from the media about his views on Yellen's nomination.
—By CNBC's Anna Andrianova. Follow her on Twitter @AndrianovaAnna