A new report by Reporters Without Borders (RSF) says China is "the world's biggest captor of journalists" with at least 127 reporters currently detained.
It said China was conducting an "unprecedented campaign of repression" worldwide against journalism.
China has justified the arrests of reporters and citizen journalists by accusing them of provoking trouble.
RSF also noted that press restrictions had worsened with the pandemic.
At least 10 journalists and online commentators have been detained for reporting about the Covid-19 crisis in Wuhan.
One of them, former lawyer Zhang Zhan, had initially travelled to Wuhan in February 2020 after reading an online post by a resident about life in the city during the outbreak.
Once there, she began documenting what she saw on the streets and hospitals in livestreams and essays, despite threats by authorities, and her reports were widely shared on social media.
She was later found guilty of "picking quarrels and provoking trouble" - a charge that is commonly levelled against activists and whistleblowers seen as undermining the government's efforts to control information in the country.
The advocacy group's 42-page report also listed how Chinese authorities used the fight against terrorism as a pretext to detain Uyghur journalists reporting on Xinjiang.
China has been accused of committing crimes against humanity against what it sees as Islamists and separatists in the majority-Uyghur region.
The report said other methods used included: using its overseas diplomatic missions to attack journalists; media blockades; censorship of topics; forcing local journalists to study Communist Party ideology and download a propaganda application on their phones; and expelling or intimidating journalists.
The BBC's John Sudworth left Beijing for Taipei in April following pressure and threats from the Chinese authorities for his reporting of China's treatment of the Uyghurs.
China also revoked the company's license to broadcast within the country in February.
A member of Bloomberg News' bureau in Beijing, Haze Fan, has also been detained since late 2020, with no information forthcoming on her case.
She was last seen being escorted from her apartment building by plainclothes officials on what Chinese authorities allege were suspicion of national security law violations.
RSF ranks China 177th out of 180 in the 2021 World Press Freedom Index, just two places above North Korea.