Convicted Wall Street fraud Bernard Madoff is dying of cancer, media reports said Monday.

The New York Post and Wall Street Journal quoted separate, unidentified sources saying that Madoff, 71, is in the terminal stages of the disease.

A spokeswoman for the federal Prisons Bureau would not make an immediate comment. However, CNBC news television earlier quoted the prisons service as saying the report was not accurate.

Madoff is serving a 150-year sentence in a North Carolina prison for a multi-billion dollar investment fraud that cheated thousands of people and institutions, including celebrities, charities and leading banks, over several decades.

The Post quoted another inmate saying Madoff's "been taking about 20 pills a day for his cancer."

"He talks about it all the time. He's not doing very well," the unnamed inmate was quoted as saying.

The Journal reported on its news blog that "sources familiar with the situation" confirmed Madoff was dying, but that it was unclear what kind of cancer he had.