RNA - Amnesty International and Human Rights Watch named six of the detainees, both men and women, and called on Saudi authorities to release them.
"It appears the only 'crime' these activists committed was wanting women to drive before [Saudi Crown Prince] Mohammed bin Salman did," said Sarah Leah Whitson, Middle East director at Human Rights Watch.
"Saudi Arabia cannot continue to publicly proclaim support for women's rights and other reforms, while targeting women human rights defenders and activists for peacefully exercising their rights to freedom of expression, association and assembly," said Samah Hadid, Amnesty's Middle East Director of Campaigns.
Amnesty denounced Saudi authorities and government-aligned media's public smear campaign to discredit the activists, whose faces have appeared online and on a newspaper front page labeling them as traitors.
Authorities said in an overnight statement that they were still identifying others allegedly involved in activities that "encroach on religious and national constants." Fellow activists said others had been arrested, but the total number was not clear yet.
The statement claimed that seven people had been arrested for suspicious contacts with foreign entities and providing enemies overseas with financial support, but did not elaborate on the issue.
In addition to agitating for women's right to drive, two detainees signed a petition in 2016 calling for an end to Saudi Arabia's male guardianship system, which requires women to obtain a male relative's consent for major decisions.
Saudi Arabia is the last country in the world to permit women to obtain driving licenses. Women will be allowed to drive starting on June 24.
In September last year, Riyadh removed the driving ban on women as part of reforms to undo the damage the kingdom has suffered for decades of human rights violations both inside and outside of Saudi Arabia.
The move came shortly after women were also permitted access into a sports stadium, for the first time, to watch a concert.
In 2016, Saudi Arabia was ranked 141 out of 144 on the Global Gender Gap Index.
In recent years, the Al Saud regime has come under intense pressure by rights groups for mistreating women.
According to Press TV, Saudi women had been banned from voting until 2015, when they were allowed to vote in local elections.
A United Nations independent expert said in January 2017 that the Saudi government should end its ban on women driving, urging the kingdom to do more to reform its male guardianship system.
Philip Alston, an Australian legal expert who reports to the UN Human Rights Council, said after a 12-day visit to Saudi Arabia that the government in Riyadh was urgently required to cast aside rules and regulations that have hampered social life in the kingdom.
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