The governments of several Gulf nations continued a crackdown on critics during the first half of 2017, Human Rights Watch (HRW) said.
In a statement on Wednesday, the international rights organisation condemned the suppression of free speech by Gulf states amid the ongoing rift between Qatar and three of its GCC neighbours - Saudi Arabia, the United Arab Emirates and Bahrain.
HRW's report listing "targeted" dissidents comes after a Bahraini court on July 10 sentenced human rights activist Nabeel Rajab to two years in prison on charges of "broadcasting false news" in a series of tweets.
"At a time when the Gulf states' open political divisions have rarely been more serious, these countries remain stubbornly united in their collective assault on their citizens' right to free speech," said Sarah Leah Whitson, HRW's Middle East director.
"Gulf states are reaching a new level of Orwellian reality when they throw citizens in jail for both criticising other Gulf nations and voicing public support for them," she said.
Hundreds of dissidents, including political activists, human rights defenders, journalists, lawyers and bloggers are imprisoned across the region, according to the group.
Among those detained is Saudi computer engineer Essam Koshak, who has been awaiting charges since January this year.
Rajab, the cofounder of the Bahrain Centre for Human Rights (BCHR), has spent several periods in prison for criticising the Bahraini government.
He was arrested in June over tweets that condemned the Saudi-led war in Yemen and Bahrain's treatment of prisoners.
Amnesty International denounced the latest sentencing of Rajab, saying it exposes a "relentless campaign" by authorities in Bahrain "to wipe out dissent".
Meanwhile, Emirati engineering student Ahmed Mansoor was arrested in March on the orders of the Public Prosecution for cybercrimes in the UAE.
In addition to direct repression, Gulf governments have acquired and deployed surveillance technology to track and monitor citizens' online activity, including Mansoor's, HRW said.
"Gulf states are intimidating, surveilling, imprisoning, and silencing activists as part of their all-out assault on peaceful criticism," Whitson said. "They should stop blocking Gulf citizens from using social and other media to push for positive reforms."
Of the 119 people Human Rights Watch listed in an interactive website of "targeted human rights activists" created in November 2016, just one was from Qatar.
Mohammed Rashid al-Ajami, who was sentenced to life in prison for allegedly insulting the emir of Qatar in 2011, was pardoned in March 2016.
To stem the flow of negative reactions, Saudi Arabia, the UAE and Bahrain took steps to curb their citizens' expression of opinions that oppose their policies.
The UAE said any objections to its measures against Qatar or expression of sympathy with Doha would be considered a crime.
Committing such a "crime" would result in a prison sentence of between three and 15 years and a fine of no less than $136,000 (500,000AED), whether on a social media platform or via any written or spoken medium, the UAE said.
The criminalisation of sympathy with Qatar was also implemented in Saudi Arabia and Bahrain.
The decision to punish citizens is a "huge violation of freedom of speech and information that could have serious implications," said Alexandra El Khazen, head of the Middle East and North Africa desk at Reporters Without Borders, a non-profit organisation promoting press freedom.
Source: Al Jazeera News