ISTANBUL — Saudi Arabia detained two dual U.S.-Saudi citizens this week during a roundup of activists, intellectuals and writers, including supporters of Saudi feminists and advocates for Palestinian rights, human rights groups and people briefed on the arrests said Friday.

The detentions, of at least 11 people, signaled a revival of a crackdown on dissent by Saudi Crown Prince Mohammed bin Salman. The campaign, marked by waves of arrests, had quieted somewhat in the months since the killing of journalist Jamal Khashoggi by Saudi agents in Istanbul.   

Many of the latest arrests occurred Thursday. Those detained included Salah al-Haidar, a dual U.S.-Saudi citizen and son of prominent feminist Aziza al-Yousef. Yousef — who is on trial with other Saudi women’s rights advocates on charges related to their activism — was temporarily released from custody last week.

Another detainee, Bader al-Ibrahim, a doctor and writer, also holds dual U.S. and Saudi citizenship, according to people briefed on the arrests, who spoke on the condition of anonymity because they feared retaliation by Saudi authorities.   

A State Department spokeswoman confirmed Friday that two American citizens had been arrested and that the United States had “already engaged the Saudi government” on the matter, but she declined to comment further, citing privacy considerations.

A Saudi government media office did not reply to an email requesting details about the detentions and the charges.    

Mohammed, Saudi Arabia’s day-to-day ruler, has loosened some social restrictions in the strictly conservative country, including lifting a ban on women driving. At the same time, he has sought to silence dissenting voices in the kingdom, as well as beyond its borders. In October, Saudi agents killed Khashoggi, a critic of Mohammed, in the Saudi Consulate in Istanbul in what the Saudi government has insisted was a botched operation to repatriate the journalist.

The Trump administration vigorously defended the Saudi government against criticism after the killing of Khashoggi, a U.S. resident who contributed columns to The Washington Post. But outrage among U.S. lawmakers over his slaying has resulted in bipartisan condemnation of the killing as well as other measures aimed at punishing Riyadh. On Thursday, the House voted to end U.S. support for the Saudi-led war effort in Yemen, after the Senate passed a similar measure last month.    

Some were puzzled by the timing of the arrests, coming barely a week after the Saudi government generated a degree of goodwill by temporarily releasing Yousef and two other women who are on trial. Several of the women’s rights activists have said they were tortured while in custody, an accusation the government has denied.  

The family of yet another Saudi detainee, Walid Fitaihi, a Harvard-trained doctor who also holds dual U.S. and Saudi citizenship, has said he has been imprisoned for more than a year without trial and has also been tortured in custody. The State Department spokeswoman said Fitaihi has been provided with consular services, adding that “we have raised and continue to raise his case on a consistent basis with the Saudi government.”

Haidar, Ibrahim and others arrested were part of a loose-knit group of writers and activists who have been supportive of the women’s rights movement and have written about other political issues, but were not considered to be especially visible or outspoken. Ibrahim had written extensively on Saudi Arabia’s Shiite Muslim minority. Another detainee, Abdullah al-Duhailan, is a journalist and novelist who has advocated for Palestinian rights, according to Amnesty International. Fahad Abalkhail had supported the campaign to lift the female driving ban, the group said.

“The Saudi Arabian authorities are shamelessly targeting those citizens who are part and parcel of the society’s vibrant intellectual, artistic, activist landscape,” Lynn Maalouf, Amnesty’s Middle East director of research, said in a statement.  

After Yousef was released last week, her family shared cheerful pictures of her homecoming, showing her posing with Haidar and other relatives in photographs that were widely shared on social media.  

Karen DeYoung contributed to this report.