Nick Xenophon's political opponents have seized on an apparent policy blunder by the SA Best leader, who appears to have significantly underestimated the state's health spending.

The former MP unveiled his health policy after critics including the Nursing and Midwifery Federation had accused SA Best of a lack of policy.

Mr Xenophon released no costed elements, but again promised to push for a royal commission into the health system.

The SA Best health policy lists its priorities as 24 dot-points.

It says "at $3.6 billion, health is one of the biggest and fastest-growing expenditure lines in the state budget".

But budget data shows SA spends significantly more that on health, with $5.948 billion provisioned this financial year — just under one-third of the entire state budget.

When asked about his information, Mr Xenophon appeared to retreat, before doubling down.

"Well, the Government has just strengthened my case that there's even greater urgency for a royal commission," he said.

"But I'm relying on the budget papers and — maybe I shouldn't have done this — I relied on some journalists."

Mr Xenophon's office later issued a clarification, saying his figure represented the net cost of the delivery of services, which does not include grants funding from the Commonwealth or revenue from private patients.

Budget data can be 'Googled'

SA Health Minister Peter Malinauskas said Mr Xenophon should simply have checked on the internet for correct information.

"It wouldn't be too hard to find," he said.

"I'm sure you could spend a couple of minutes on Google to see it.

"The health expenditure of the state is $5.9 billion. It's a very significant component of the overall state budget and one would have thought, if they were releasing a health policy, it's a number they'd get right."

Liberal health spokesman Stephen Wade said it was evident SA Best had a poor grasp of health expenditure.

"The fact that the only figure in the whole press release is a 40 per cent understatement of the state's spending on health shows that Nick Xenophon is not worthy to be premier of this state, let alone kingmaker of the next government," he said.

Mr Xenophon said the health inquiry he was demanding should examine the troubled history of electronic patient records, since the Enterprise Patient Administration System (EPAS) started being rolled out across public hospitals.

"If you spend a bit of money on a royal commission now, you could save hundreds of millions of dollars down the track and, most importantly, get better outcomes for patients," he said.