Saudi Arabia has detained a prominent Islamic scholar and three of his sons, activists said Thursday, in a widening crackdown against clerics, intellectuals and rights campaigners.

Rights campaigners and online activists said Sheikh Safar al-Hawali, a Sunni scholar and leading figure in Saudi Arabia’s Islamic Sahwa reformist movement, had been taken into custody, the Middle East Eye reported.

London-based Saudi rights group ALQST said the arrests happened after Hawali published a book critical of the Saudi royal family. ALQST’s Yahya Assiri told Reuters the arrests took place on Wednesday.

Saudi Crown Prince Mohammed bin Salman, named heir to the throne in June 2017, has spearheaded a widening crackdown on dissents under the pretext of changes and reforms.

Authorities last month arrested a number of prominent women’s rights campaigners, just days before the kingdom ended a decades-long ban on women driving.

Hawali was jailed in the 1990s for opposing his country’s ties to US troops leading a military operation to expel Iraqi forces from Kuwait.

In 1993, he was banned from public speaking and dismissed from his academic posts along with prominent cleric Sheikh Salman al-Awda.

While no charges were pressed, the two were accused of aiming to incite civil disobedience. They were arrested again in 1994 but soon released.

Source: Middle East Eye and Reuters