Identity thieves used the early superannuation removal scheme to defraud up to 150 Australians of thousands of dollars from their super accounts.

The Australian Tax Office (ATO) confirmed media reports of the fraud during a Senate committee on Thursday with ATO Commissioner, Chris Jordan saying “some limited fraudulent activity” had been spotted and “immediately acted upon”.

Authorities learned of the fraud on April 30 when a superannuation fund notified AUSTRAC of suspicious activity.

At last week’s senate hearing, Australian Federal Police (AFP) Commissioner, Reece Kershaw, said the police had executed five search warrants but made no arrests.

“We have identified some bank accounts and had those bank accounts frozen, with approximately $120,000 all up,” Kershaw told the Senate committee.

“We don't want to tip-off the offenders involved in this, given the fact that we have made no arrests at this stage.”

When pressed about media reports saying the ATO had been hacked, Kershaw said “no government system has been [breached]” but there was an intrusion into a “third party which sits outside the government”.

Shadow Finance Minister, Katy Gallagher, was critical of the verification processes that allowed people to be defrauded of their superannuation.

“Part of the problem with the early access super one is that it is a self-verification process,” Gallagher said in a statement.

“There is no testing done by the ATO to verify that document. You sign it and therefore they believe you.

“Obviously that has fallen short and I think they should get right across it before it extends to other programs.”

Reddit user withintheskin posted about the fraud on Wednesday last week after receiving an email from their super fund about withdrawal application they did not submit.

“Luckily, my superannuation fund does their own assessment independent of the ATO and stated for the release to go ahead I need to contact them,” the user said.

After checking their MyGov account, withintheskin found their mobile number, email address, and bank details had all been changed.

Over 1.2 million people signed up to withdraw some $10 billion from superannuation accounts across the country.

But the government had to pause the early access scheme following the fraudulent activity.

On Monday, the scheme resumed with updated verification measures.

Assistant Treasurer, Michael Sukkar, said in a statement that the ATO was working to improve the security of the “small number of third parties who could be susceptible to criminal activity”.

“Additional risk filters will also be applied by the ATO on all files before they are delivered to funds, and additional information will be provided to funds to assist them in discharging their own obligations to apply fraud prevention processes,” Sukkar said.

“The ATO is also using this as an opportunity to remind Australians to be vigilant with how they store and share their personal information.”