Saudi Arabia claims it has released 11 citizens who were detained last month "for questioning over suspected links to foreign entities", Reuters reported.
The ultra-conservative kingdom launched a renewed campaign of "arbitrary" arrests of at least 12 people, including writers and academics, at the end of November.
A Saudi official told Reuters that the detainees were questioned over their ties with foreign groups and that none have been indicted.
The case remains open, however, and charges could still be issued.
Prisoners of Conscience, a campaign group that tracks Saudi prisoners, said on 24 November that the kingdom had detained a number of "academics, Twitter activists, and even women".
The detentions were also noted on Monday by ALQST, a UK-based Saudi human rights organisation which confirmed the arrests of at least nine writers and journalists.
Neither group has confirmed the release of all the detainees.
The ultra-conservative kingdom became the first Arab nation to take over the G20 presidency Sunday as it continues to face strong criticism over a crackdown on dissent and the murder last year of journalist Jamal Khashoggi.
Amnesty International said world leaders must address Saudi Arabia's heinous human rights record Thursday, as Riyadh prepared to assume the G20 presidency.
"Saudi Arabia steps up to the G20 presidency amid a new wave of arbitrary arrests of peaceful critics, with many human rights defenders still languishing behind bars, and just over a year since the horrifying killing of Jamal Khashoggi," said Heba Morayef, Amnesty International’s MENA regional director.
Bader Al-Rashed, Suleiman Al-Nasser, Waad Al-Mohaya, Musaab Fouad Abd al-Kareem and Abdul Majid al-Balawi were arrested after their homes in the Saudi capital Riyadh were raided on 16 November, ALQST said in a statement issued last week.
The detentions were followed by the arrests of writer Abdul Aziz al-Hais in the northwestern city of Hail, writer Abdul Rahman al-Shahri in the southern city of Abha and activist and blogger Fouad al-Farhan in the coastal city of Jeddah last week, the organisation said.
Prisoners of Conscience also confirmed the arrests of Nasser and Mohaya, as well as the detentions of writer Badr Al-Rashid, journalist Maha Al-Rafidi and a writer identified with the initials M. F. by the group.
ALQST added that it had received unconfirmed reports of the arrest of journalist Zana Al-Shahri.
"Undertaking a new arrest wave against independent thinkers, activists, and writers shows that Saudi authorities haven't learned any lessons from the Khashoggi affair and feel there are no real negative consequences for continuing their massive repression campaign against independent Saudi voices," Adam Coogle, Middle East researcher for Human Rights Watch, told The New Arab.
The wave of detentions comes just days ahead of an anticipated verdict in the case of imprisoned Saudi cleric Salman Al-Odeh.
Odeh's family and Saudi media have previously reported the prosecution is seeking the death sentence for the Islamic scholar.
According to relatives, the cleric was embroiled in Saudi Arabia's diplomatic row with Qatar. Riyadh reportedly asked religious and other dissidents to publicly express support for the kingdom's blockade on Doha, but Odeh refused.
He was among 20 people, including writers and journalists, arrested in a 2017 crackdown on dissent in the kingdom.
Those arrests were followed last year by the detention of 11 women right's activists, including long-time campaigner for women's right to drive Loujain Al-Hathloul.
Several of the women, including Hathloul, have alleged they have faced torture and sexual harassment while in detention.
Saudi authorities have offered to release Hathloul in exchange for her video testimony denying that she had been tortured in prison, her family claimed earlier this year.
At least nine more dissident writers and academics were jailed by the kingdom earlier this year.
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