A Chinese blogger jailed for four years for her reporting on the first Covid outbreak in Wuhan has been released from prison, Reporters Without Borders (RSF) has confirmed.
The media watchdog shared a video of Ms Zhang saying she had been released on schedule, thanking everyone for their concern.
She was due to be freed last week but friends and supporters were concerned when they were unable to contact her.
A former lawyer, Ms Zhang travelled to Wuhan to document the government's response to the outbreak in a series of widely-shared online videos.
Media watchdogs and human rights groups had said that Ms Zhang was wrongfully prosecuted.
RSF says her freedom is extremely limited.
In the short video posted online the 40-year-old is wearing pyjamas, standing in a hallway. In a very soft voice she says she was allowed to go to her brother’s house on 13 May.
She thanks people for their concern regarding her wellbeing.
In February 2020 she travelled from her home in Shanghai to Wuhan at the beginning of the Covid crisis, and took videos which were critical of hospital overcrowding, the harassment of victims and alleged cover-ups regarding the true death toll.
Her livestreams and essays were widely viewed on social media, and she continued to produce them despite threats from authorities.
Ms Zhang was imprisoned in May 2020 for the crime of “picking quarrels and provoking trouble”, a frequent charge against activists in China.
She refused food in the first few months of detention, and her lawyer had said she was then being force-fed through a tube. She remained on partial hunger strike until July 2023, when her weight had reportedly halved to just 37kg (81.6lb).
She was also suffering from severe malnutrition, gastrointestinal disease, and low white blood cell count, RSF said.
Her supporters say that, although she has now been released from prison, she remains under close scrutiny by the authorities.
When the pandemic first struck in early 2020, the Chinese internet - despite being heavily censored - was inundated with messages describing government cover-ups and failures in the healthcare system.
But the state's censorship machine suppressed the unprecedented online anger.
The Communist Party filled state media with positive stories about its Covid-19 response. In February 2023, the party's top leaders declared "victory" over the virus and described the government’s response to Covid-19 as “a miracle”.