A consultant at St Vincent's hospital in Dublin says he is disassociating himself from any connection with the hospital group or foundation.
Professor John Crown, who is also a member of the Seanad, says the board of the hospital do not enjoy his confidence.
He has told the Seanad that staff at the hospital in 2002 were "deliberately and fraudulently" charging private health insurers for cancer drugs which had been provided for free.
Professor Crown says he now has documents which he is willing to discuss with the Health Minister James Reilly.