By Martha Graybow

"We are looking at frauds on charities and people who may have defrauded charities" in the Madoff case, New York Attorney General Andrew Cuomo told reporters after a news conference on an unrelated matter.

"I don't want to comment on who we are investigating or not by name," he said, adding that the probe was "not looking at Mr. Madoff" himself at this time.

Authorities say the veteran money manager, who was charged with securities fraud by federal prosecutors in Manhattan, confessed to a $50 billion investment fraud a month ago.

Big banks, the wealthy, funds and charities have all declared themselves victims of Madoff, a former chairman of the Nasdaq stock market.

Cuomo, whose office has not previously publicly declared a probe of the purported worldwide Madoff fraud, said the impact of the alleged scam on charities and other groups in New York had given his office "great cause of concern."

"These are important charities and not-for-profits to the state of New York," he said. "We have a particular interest in protecting charities in the state and regulating charities."

On Monday, a U.S. magistrate judge rejected a government request to revoke's Madoff's bail and send him to jail while the investigation of his alleged fraud proceeds.

The 70-year-old investment adviser remains under house arrest in his $7 million Manhattan apartment.

Madoff's lawyers have said their client has been cooperating with government investigations following his December 11 arrest for what would be the biggest Ponzi scheme in history. In a Ponzi scheme, early investors are paid with the money of new clients.

(Additional reporting by Grant McCool, editing by Maureen Bavdek)