Religious scholar Sheikh Safar al Hawali has been detained for criticising the Saudi royal family in his book. Hawali was previously jailed for opposing his country's ties to US troops.
Saudi Arabia has detained a prominent scholar, activists said on Thursday, in a widening crackdown on dissent in the conservative kingdom, which is undergoing sweeping economic and social reforms.
Rights campaigners and online activists said Sheikh Safar al Hawali, a Sunni scholar and leading figure in Saudi Arabia's Sahwa reformist movement, had been taken into custody.
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.
They did not give further details about the case of the scholar, who has pushed a line of anti-Americanism and Islamic rule.
Saudi Crown Prince Mohammed bin Salman, named heir to the throne in June 2017, has spearheaded a string of reforms over the past year aimed at improving his country's image and economy.
The changes have coincided with a widening crackdown on all forms of opposition.
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.