Claims that hospital waiting lists will be blown out under changes to the medicare levy surcharge have been hosed down by the federal government.
Catholic Health Australia which runs 21 hospitals, warns Labor's budget changes could see an extra 200,000 patients added to waiting lists a year.
The organisation also warns of a $400 million a year cost to the public sector.
But health minister Nicola Roxon said the claims were extreme.
"You have to make a very large number of quite bold assumptions for catholic health australian's estimations to be expected," she said.
She said there were many variables why familes choose private health insurence.