Law enforcement authorities arrested activists Nouf Abdelaziz and Mayaa al-Zahrani earlier this month, along with 14 other women's rights activists attempting to abolish the Islamic kingdom's male guardianship system, according to the rights group.
The activists are charged with "forming a cell that threatened Saudi security," according to the Saudi government.
"Saudi authorities have arrested two more women's rights activists… in what appears to be an unrelenting crackdown on the women's rights movement," HRW said Wednesday.
"Saudi activists have reported that the authorities have placed travel bans on numerous others since May 15," the New-York based watchdog added.
Saudi Arabia has extremely restrictive laws governing the lives of women and curtailing their autonomy. "Under Saudi Arabia's discriminatory male guardianship system," Human Rights Watch says, "every woman must have a male guardian — a father, brother, husband, or even a son — who has the authority to make a range of critical decisions on her behalf. Women are required to receive guardian approval to apply for a passport, travel outside the country, study abroad on a government scholarship, get married, or even exit prison."
Female Saudi activists started the hashtag #AbolishGuardianship in July 2016, which has proven to be an effective method of organizing, considering 40 percent of the country's 6.3 million Twitter users are women, the Guardian reported last month.
According to HRW, activist and writer Abdelaziz was arrested on June 6 after she publicly voiced her solidarity with the previously detained activists. A few days later, Zahrani was also arrested after she publicly shared the case of Abdelaziz's arrest. Both women are being held incommunicado, according to HRW.
"The Saudi government appears determined to leave its citizens without any space to show even rhetorical support for activists jailed in this unforgiving crackdown on dissent," said HRW's Middle East director Sarah Leah Whitson.
"Nouf Abdelaziz and Mayaa al-Zahrani's only 'crime' seems to be expressing solidarity with their fellow imprisoned activists," Whitson added.
On June 4, local newspaper Okaz stated that nine detained activists will soon be referred to the Specialized Criminal Court to be tried for "cooperating with entities hostile to the kingdom, recruiting persons in a sensitive government agency to obtain confidential information to harm the interests of the kingdom and providing financial and moral support to hostile elements abroad," HRW reported Wednesday.
Although Saudi Arabia continues to imprison women activists, Riyadh has made strides toward liberalization of social norms in the kingdom. For instance, some women will be to drive legally on June 24.
On May 28, the Shura Council, the kingdom's formal advisory body, passed a draft law that will require offenders to spend up to five years behind bars and pay a maximum penalty of $80,000 if they're found guilty of sexual harassment. The law was approved by the Saudi cabinet, the Saudi Press Agency reported last month.