Lessons from the unlawful robodebt scheme still need to be learnt, Opposition Leader Peter Dutton says, after the federal corruption watchdog declined to investigate senior officials involved in the scheme.

The National Anti-Corruption Commission said on Thursday that while it had received referrals to investigate six senior public servants in relation to the robodebt scheme following a royal commission, it would not start a fresh inquiry.

“The conduct of the six public officials in connection with the robodebt scheme has already been fully explored by the robodebt royal commission and extensively discussed in its final report,” a spokesman for the commission said.

“After close consideration of the evidence that was available to the royal commission, the commission has concluded that it is unlikely it would obtain significant new evidence.”

Speaking after the decision was handed down, Dutton said the failures of robodebt still needed to be heeded.

“There were lessons to learn and there’s obviously been a lot written in relation to that,” he said in Melbourne on Thursday.

“We want to make sure that we’ve got appropriate use of taxpayers’ money and where that money is wasted, or where somebody has falsely claimed, then there’s a debt to the Commonwealth, and people ultimately have worked hard for that money to pay that welfare benefit.

“There are lessons from robodebt, we can certainly learn from that experience.”

The robodebt scheme ran from 2015 to 2019 under the former Coalition government. It used annual tax office data to calculate average fortnightly earnings and automatically issue debt notices to welfare recipients.

Hundreds of thousands of Australians were ensnared by the program, which illegally recovered more than $750 million and was linked to several suicides.

There was a royal commission into the scheme, with an almost 1000-page report handed down in July 2023. It recommended individuals involved be referred for criminal prosecution.

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-AAP