A PhD candidate at a prestigious Australian university and father of two has been charged after police allegedly found more than 25,000 child abuse videos and images on his phone.

Ali Alghamdi, a 35-year-old Saudi Arabian national, was arrested at the University of NSW’s Randwick campus about 3pm on Monday.

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He was identified as a suspect in the online distribution, supply, and access of child abuse material after a strike force trawled the dark web in late 2022.

Police allege that during a search of his phone, they located more than 25,000 videos and images of child abuse material, with 42 marked as “favourites”.

He was charged with using a carriage service to access child abuse material.

The part-time Uber driver faced court on Tuesday, where it was revealed the alleged material was “significantly depraved”, involving children between the ages of two and four, as well as infants.

The material was described as too graphic to be published.

Commonwealth prosecutor Melanie Tam told the court Alghamdi denied knowing about the 42 favourited files and claimed he had obtained the content in order to report it to authorities, The Sydney Morning Herald reported.

He allegedly stored child abuse content on encrypted messaging apps, and one of his three email accounts reportedly contained nearly 650 gigabytes of material.

According to Alghamdi’s LinkedIn and UNSW profile, he began a Master’s degree in Optometry at UNSW in 2020, funded by a scholarship from the Saudi Ministry of Health.

He then received the University International Postgraduate Award (UIPA) scholarship to undertake a PhD in Optometry in 2022.

Before coming to Australia, he completed his bachelor’s degree in optometry at King Saud University in Saudi Arabia in 2014 and worked as an optometrist for three years at a general hospital there.

The court heard his wife joined him in Sydney six weeks ago and currently lives in Waterloo.

In a translated reply on Facebook, Alghamdi wrote to someone: “May God protect your children, and may we see you in good health, God willing.”

Magistrate Michael Barko refused bail, describing Alghamdi as an “extreme” flight risk due to his student visa status.

“They searched devices which contained film which could only be said to be the most perturbing child sexual abuse,” he said.

Alghamdi is due to return to court on September 23.