A prominent Saudi scholar and Snapchat influencer has been arrested by Saudi authorities in what experts said was evidence of the kingdom’s extreme crackdown on social media users.

The arrest of Mohammed Alhajji, a public health expert who completed his dissertation in the US, follows the disappearance and recent arrests of other prominent influencers for “crimes” that include the perceived criticism of the crown prince, Mohammed bin Salman, and support for women’s rights.

Alhajji’s arrest was confirmed by two sources with close knowledge of the matter.

There was no indication of why the influencer – who was seen as apolitical and supportive of the Saudi government – was detained.

Alhajji had been scheduled to speak at an event in Riyadh on Sunday, but observers noted that a tweet describing the event had been deleted in recent days.

It followed the recent news of the arrest of Manahel al-Otaibi, a 29-year-old certified fitness instructor and artist who frequently promoted female empowerment on her social media accounts. Among other charges, Otaibi was accused by Saudi authorities of using a hashtag – which can be translated as #societyisready – to call for an end to male guardianship rules. Another Snapchat influencer, Mansour Al-Raqiba, who had more than 2 million followers, was sentenced to 27 years in jail for allegedly privately criticising the crown prince.

In one of his last Washington Post columns before his brutal murder in 2018, Jamal Khashoggi, the Saudi journalist, criticised waves of arrests by the crown prince’s government and the “public shaming of intellectuals and religious leaders who dare to express opinions contrary to those of my country’s leadership”.

Yahya Ibrahim Assiri, a UK-based Saudi dissident and founder of human rights group ALQST, said Saudi Arabia was no longer seeing “mass arrests” as described by Khashoggi five years ago.

“The prisons are full and the society is completely threatened. No one criticises the violations or the corruption,” Assiri said. “However, the authorities are still looking for more victims and still targeting anyone they feel could express their opinion at any time. Alhajji is not criticising the authorities – he is trying to be on the safe side – but he has been arrested unfairly, like a lot of people.”

Alhajji has a verified Snapchat account and 385,000 followers on Twitter. In interviews highlighting his academic success in the US, where he attended graduate and undergraduate university, Alhajji was described as a social media personality who wanted to use his platform to explain public health issues to a Saudi audience.

“It’s like a reality TV show, a lens for people 7,000 miles away to observe my PhD life in the US, my life in Philly,” he was quoted as telling a Temple University news outlet.

Describing his then recent move back to Saudi Arabia, he noted that he had built enough of a following to get recognised. “They call me Dr Mohammed,” he said. Alhajji graduated from Temple with a PhD in 2020. His research on the spread of sickle cell disease, a common genetic disease in Saudi Arabia, earned him an award from the American Public Health Association Genomics Forum and the Society of Behavioral Medicine.

Sarah Leah Whitson, executive director of Dawn, a human rights group founded by Khashoggi, said Saudi Arabia was notably now arresting prominent voices that had “nothing to do with politics” because any independent voice was seen as a threat in the mind of “MBS”, as the crown prince is known. The disappearance of people like Alhajji, for no known reason, was one of the “terror” tactics used by the crown prince, she said.

“MBS also knows he’s free to do whatever he wants in the country because he is secure in his impunity, with the likes of Biden, Macron and Sunak falling over themselves to woo him for weapons purchases and happy to look the other way about anything else,” she said.

Alhajji was described by those who have followed his work as member of Saudi Arabia’s elite, who had formerly represented the Misk Foundation, a government organisation meant to encourage Saudi youth, which was founded by Mohammed bin Salman. He also appeared before a UN body in 2019 representing Saudi Arabia.

Omar Abdulaziz, a Canada-based Saudi dissident who was a close confidant of Khashoggi’s, said it was “shocking news” given that Alhajji was largely seen as a supporter of the current government.

Social media companies have declined to comment on the disappearances and arrests of their most prominent users in the kingdom, including the decades-long sentences against two women – Noura al-Qahtani and Salma al-Shehab – for tweets and likes on Twitter that were deemed offensive.

Snapchat CEO and founder Evan Spiegel was in Saudi Arabia in December 2022. The company, which has more than 20 million users in the kingdom, including an estimated 90% of 13-to-34-year-olds, declined to comment on Alhajji’s arrest.

The Saudi embassy in Washington did not immediately respond to a request for comment.