Reports of diverted RAT shipments rile SA

South Australia has asked regulators to investigate reports some rapid antigen tests bound for SA have been improperly diverted to other states.

Premier Steven Marshall says both the NSW and Victorian governments have denied requisitioning tests at Sydney and Melbourne airports.

Prime Minister Scott Morrison has also ruled out the federal government being involved in any way, describing the allegations as "absurd".

But Mr Marshall says reports that tests have gone missing are serious and he has written to Australian Competition and Consumer Commission boss Rod Sims asking him to investigate.

"If these allegations prove correct, it's quite possible that they are illegal, anti-competitive and, of course, they're a massive kick in the guts for South Australia," the premier said.

"If they (the tests) have been taken by another state, that's outrageous."

Asked about the issue earlier, Mr Morrison said suggestions the Commonwealth had redirected supplies of rapid antigen tests, or impounded private supplies were not true.

"I have no idea where that's coming from and you know, it just floats around on social media and then it gets reported," he said.

"I mean, something happening on social media isn't a story. It's usually just rubbish."

Also on Wednesday, Mr Marshall said the state government had ordered an additional five million test kits to cater for growing demand.

He said that was on top of the 1.4 million kits SA Health already had in stock and the 200,000 currently arriving on a daily basis.