Australian authorities have ordered Google to destroy all data it deliberately harvested while operating specially equipped cars for its Street View service in 2010.
Australia's privacy commissioner Timothy Pilgrim told Google that he was "concerned" over revelations of extra data being found, "particularly as Google had advised that the data was destroyed."
"Organisations that retain personal information that is no longer required could leave individuals at risk should it be misused," Pilgrim wrote in an email dated August 6.
"I appreciate your advising me of this matter, and look forward to confirmation that the data has been destroyed," he added.
According to The Herald Sun, Pilgrim said he also wanted confirmation from an independent third party that the data had been destroyed.
He also said that Google must undergo an audit to ensure no more was being held, the report said.
Google is facing over 12 lawsuits across the world for intercepting users' private data through unsecured Wi-Fi connections.
The firm has been fined by regulators in the US for violating privacy laws and has contacted governments in the UK, Ireland, France, the Netherlands, Norway, Finland, Sweden, Switzerland and Austria about the security breach.