At least 30 people have been rounded up in recent days in Saudi Arabia in an apparent sweep against Islamist sympathisers and critics of the crown prince.
Saudi rights activists say among those reportedly detained are popular clerics, writers, a poet and prominent intellectuals.
The government has released a vague statement confirming arrests were made against people working against the interests of Saudi Arabia, but did not name the detainees.
The arrests have thrown an already anxious kingdom into deeper unease, raising questions about the country's steadiness amid mounting speculation that Crown Prince Mohammed bin Salman could soon replace his father as king.
The arrests appear to be linked to a three-month impasse between Qatar and Arab states that have severed ties over the small Gulf state's embrace of Islamist groups.