The Wollongong worker had just finished transferring data from Paul McKenzie George Ferguson's old Samsung Galaxy S5 to his new Samsung Galaxy S10 on the morning of March 13 when she discovered more than one hundred child abuse images as she carried out a routine check to see if the transfer had been successful.

She handed the new phone back to Ferguson and he left the store.

At lunchtime, she and another colleague attended Wollongong Police Station during their lunch break to report what they had seen.

Police went to Ferguson's house later that afternoon and carried out a search warrant, which included seizing and searching his mobile phone.

Officers discovered multiple images of young females which they deemed child pornography.

When questioned, the 60-year-old admitted to downloading and possessing the child abuse material stored on his phone.

He said there were "thousands" of similar images on the device, mainly containing adolescent females aged between 10 and 18.

He was arrested and charged with one count of possessing child abuse material, to which he pleaded guilty in court on Tuesday.

However, defence lawyer Paul Paine noted the police fact sheets did not contain a breakdown of the severity of the images - vital information in determining sentence - and sought an adjournment for one to be obtained.

Ferguson will remain on bail, which includes the conditions that he not access the internet or go within 200m of any school or playground, ahead of his sentencing in August.