The federal health department will investigate reports of the use of unqualified and trainee doctors under the after-hours GP service.
Claims that after-hours GP services are relying on trainee and unqualified doctors will be investigated by federal health officials.
But the peak body for after-hours medical deputising services insists every doctor is fully qualified.
News Corp on Thursday revealed unpublished Medicare data showing 70 per cent of the 1.86 million after-hours house calls in 2015-16 were made by non-vocationally registered GPs and GP trainees.
The report included allegations a Sydney-based private equity firm which majority owns the National Home Doctor Service is legally making millions from Medicare funds.
Health Minister Greg Hunt says the claims raise two issues - the need for best-quality patient care and the inappropriate claiming of rebates, already raised in the government's Medicare review.
"The company has denied (the claims), and they are entitled to have their right to put their side, but the (Australian Medical Association) and the Royal Australian College of General Practitioners, two of the most reputable medical bodies in the country, have their concerns as well," Mr Hunt said.
"So this is a moment of reckoning."
Mr Hunt confirmed those offering such services have to be qualified as a doctor but, because of a longstanding rule, not as a GP.
The National Association for Medical Deputising Services says every doctor who works after hours is registered with the government's own registration body.
"They are fully trained doctors including emergency specialists and have an average twelve years post graduate experience," it said in a statement to AAP.
"Without the service, there would be more than one million extra unnecessary emergency department presentations every year."
The association said any instance of inappropriate billing should result in the doctor being referred to the Professional Services Review for examination.
In June the government's Medicare review recommended rebates for some visits by home doctors be cut, so only a patient's usual GP could claim the full $130 rebate for an urgent after hours call.
The preliminary report found the existing system does not represent value for money for the taxpayer, while for those working for deputising services, the after-hours period is in effect their normal business hours.
The Medicare Benefits Schedule Review Taskforce also found:
* The number of urgent after-hours services increased by 150 per cent in the five years between 2010-11 and 2015-16. Standard GP services grew by just 15 per cent.
* Benefits paid similarly rose from $90.8 million to $245.9 million over the five years.
Mr Hunt says reforms are coming on the back of the review's final report due in coming weeks and he is "very drawn" to what is being suggested.
Prime Minister Malcolm Turnbull says his minister is very focused on the issue.
"Any drop in quality of service, any report of that, whether it's right or not, is of great concern, I can assure you that," he told reporters in Brisbane.