Australia's coronavirus immunisation program has lagged behind almost all the developed world for most of this year.

While rates are picking up, just 29.1 per cent of Indigenous Australians aged 16 and above are fully vaccinated compared with more than 53 per cent of the general population.

Mr Turnbull - who Scott Morrison replaced as prime minister after a 2018 leadership spill - didn't mince words in assessing the rollout.

"The reason we are in lockdown is because the federal government did not buy enough vaccines last year," he told the National Press Club on Wednesday.

"There is no argument about that. It's the biggest failure of public administration I've ever witnessed."

The former Liberal leader said Indigenous communities should have been provided with vaccines at the earliest possible opportunity.

"It is extraordinary that you've got vulnerable communities that are actually lagging behind the mainstream of the community - the big cities in Sydney and Melbourne and so forth," Mr Turnbull said.

"It's a failure of administration. I'm sure it is not a policy issue.

"It's just that they did not get their act together, they let us down and they let down Indigenous communities particularly."

He said it would have been "so easy" to do deals with Pfizer and Moderna for more vaccines earlier in the rollout.

The Morrison government has blamed vaccine hesitancy for low Indigenous vaccination rates and insists there were no imported doses available to Australia earlier.

Labor's health spokesman Mark Butler said Aboriginal and Torres Strait Islander people had been left behind in the rollout along with other vulnerable groups.

Australian Associated Press