Saudi security officers have tortured jailed women’s-rights activists as part of a government campaign to squelch criticism of Crown Prince Mohammed bin Salman that began before last month’s killing of dissident journalist Jamal Khashoggi, according to people familiar with the situation.

At least eight of the 18 women’s-rights activists detained by Saudi authorities this year have been tortured, including at least four who were subjected to electric shocks and lashings, according to two advisers to the Saudi royal family, activists and others with knowledge of the prisoners’ treatment.