The Minister for Health, Mr Martin, yesterday stressed the need for members of the public to make sure doctors they attended were registered.
His comments followed the screening of an RTÉ Prime Time programme on Tuesday night which highlighted the case of Dr William Porter, a doctor struck off in California, but who was treating cancer patients in a Co Clare clinic despite the fact that he is not registered as a doctor here.
During the programme, the president of the Medical Council, Prof Gerard Bury, warned people about Dr Porter's practice.
"At this stage our concerns about Dr Porter's practice are such that we believe it is responsible and reasonable to alert the public to potentially difficult or perhaps even dangerous practice," he said.
He added that the Medical Council, which regulates registered doctors, had no power to intervene in this case because the doctor was unregistered.
Mr Martin said yesterday he would repeat Prof Bury's warning, adding that "the public need to be clear that doctors they are dealing with are on the register".
He added that a Bill now being drafted would try to deal with doctors not on the register who were practising medicine. The heads of the bill would be published before Christmas, Mr Martin said.
Dr Porter, who worked as an eye surgeon in California, was struck off for "gross negligence".