DUBAI, United Arab Emirates (AP) — Saudi authorities have released two prominent women's rights activists, but continue to hold at least eight others in a sweep targeting prominent icons of the women's rights movement, activists and rights groups said Thursday.

They say the two released are Aisha al-Mana, 70, and Hessah al-Sheikh, a professor at King Saud University who volunteers with Saudi-based charities focusing on women and children. Both women are longtime advocates of women's rights and took part in the first protest in 1990 against the kingdom's ban on women driving, in which nearly 50 women were arrested and had their passports confiscated.

Amnesty International and two Saudi human rights groups operating abroad said the conditions of al-Mana's release remain unknown. Activists had said al-Mana previously suffered a stroke and were concerned for her health while under arrest.

People familiar with the arrests told The Associated Press authorities had also released al-Sheikh. They spoke on condition of anonymity for fear of repercussions.

Activists and rights group say those still detained — five women and three men — have been interrogated without access to lawyers and have been allowed just one phone call to relatives since their arrest last week. One of the women has been held entirely incommunicado since her arrest May 15.

The detentions are seen as a culmination of a steady crackdown on perceived critics of the government. In recent weeks, activists say dozens of women's rights campaigners have also been banned from traveling abroad.

The arrests have cast a pall over recent social openings being pushed by Crown Prince Mohammed bin Salman, including a historic decision to lift the world's only ban on women driving next month.

The arrests have also attracted negative publicity amid the crown prince's efforts to brand himself a "reformer."

"He wants to rule without so much as a whisper of criticism," wrote the Washington Post's editorial board this week. "The crown prince seeks to modernize the kingdom but seems not to recognize the essential role of freedom in a modern society."

Several of those caught up in the sweep are successful, highly-regarded professionals and pioneers in their field in Saudi Arabia.

Al-Mana is the director of Al-Mana General Hospitals and the Mohammad Al-Mana College of Health Sciences. She completed her bachelor's and master's degrees in the U.S. in sociology. In 1980, she became one of the first Saudi women to obtain a Ph.D., also in the U.S.

In 2016, she established a scholarship program for Saudi women to study global health at her alma mater, the University of Oregon. She also established a $2 million endowment to support Saudi and Arab women at the American University of Beirut who are studying advanced degrees in nursing and health sciences.

Al-Sheikh hails from a prominent family in Saudi Arabia and co-authored a study published this year by the Center for Women's Global Leadership in partnership with Rutgers University that examines Saudi women's advocacy since 1990.

The release of the two women signals a possible breakthrough for those still held, who include Loujain al-Hathloul, Aziza al-Yousef, Madeha al-Ajroush and Eman al-Najfan — four well-known Saudi women's rights activists who range in age from their 20s to their 60s.

Ibrahim al-Mudaimigh, one of the kingdom's most well-known lawyers, is also among those detained. He holds a doctorate from Harvard Law School and has supported human rights defenders for decades and has offered legal representation to activists in the kingdom.

The sweep against the group began last week when police arrested the 10, some of them in the capital, Riyadh, and transferred them to the city of Jiddah, where the king, crown prince and top officials are working during the month of Ramadan.

Saudi media say the arrests were carried out by forces from the Presidency of State Security, a body that reports directly to the king and crown prince.

The Interior Ministry has not named those arrested but said the group is being investigated for communicating with "foreign entities," working to recruit people in sensitive government positions and providing money to foreign circles with the aim of destabilizing and harming the kingdom.

Pro-government media outlets have splashed some of the women's photos online and in newspapers, accusing them of being traitors and of belonging to a "spy cell".

Activists told the AP that seven of those detained were involved in efforts to establish a non-governmental organization called "Amina" that would offer support and shelter to victims of domestic abuse. They had recently submitted their request to the government to establish the NGO.

Al-Mana was not among the seven involved in trying to establish the NGO, but al-Sheikh was, according to activists who spoke to the AP.

Over the past years, authorities have steadily cracked down on human rights advocates, including some dozen members of the now dissolved Saudi Association for Civil and Political Rights, known by its Arabic acronym HASEM. The group's founding members are serving lengthy prison terms under a sweeping anti-terrorism law dating back to 2014, which defines acts as vague as "defaming the state's reputation" as terrorism.

The crown prince last year detained dozens more perceived critics of his foreign policies, and many remain imprisoned without charges or trial. He also led an unprecedented shakedown of top princes and businessmen, forcing them to hand over significant portions of their wealth in exchange for their freedom as part of a purported anti-corruption campaign.