While the grandfather said he does not blame the store or its staff for the incident, he said the issue is a “symptom of society”.

“I was shocked because I didn’t think it was that easy to do. It would be the last place I’d expect to see it,” the 71-year-old said.

His 12-year-old granddaughter stumbled across the images after she accessed the internet on a display smartphone and tablet in the independently owned store.

“This could happen anywhere, and they need to have a setup that prevents it from happening. It’s a national issue,” the grandfather said.

“People need to be aware it can happen in any store, anywhere, if they don’t protect their devices.”

Telstra said they take “inappropriate use” of display devices “extremely seriously”, and have apologised for the incident.

“Our store staff, including at the independently owned Telstra store in question, constantly monitor the devices, including regular content checks, and we continue to investigate other security measures,” Telstra area general manager Chris Taylor said.

“All our stores are also equipped with CCTV cameras and we are now reviewing vision to establish who may have accessed the content in the first place.”

The grandfather said he is “absolutely terrified” other children across the country may be able to access explicit images, even if parents monitor their children’s internet use at home.

“My granddaughter was distressed. And just how many more school kids have experienced it?” he said.

“Something has to be done.”