A Ming had described how his father probably contracted the coronavirus that causes Covid-19 during a visit to Wuhan Union Hospital at the beginning of January for a health check-up. There were no safety precautions in place at the time.

“Everybody thinks Mr A Ming is very brave. He feels that since he has experienced these things, he should share them,” Chen said.

During their conversation Chen noted that “many people are worried I will be detained” and he was last heard from on February 7.

His friend Xu Xiaodong, an MMA fighter who has become well known for challenging and defeating traditional martial arts practitioners, said Chen had been forcibly quarantined but no one knew where he was.

Coronavirus lockdown in Wuhan means foreign residents with no flight out must sit tight

Fang was taken away by plain-clothes police two days later, according to the Hong Kong broadcaster RTHK.

The Wuhan resident had become well known for the videos he filmed at the city’s hospitals and had called for people to resist the Communist Party.

The pair were two of the most high-profile citizen journalists documenting the Covid-19 outbreak and highlighting stories that did not appear in China’s tightly controlled state media, including photographs of dead bodies in hospital corridors and piled up in vans.

Although some established media outlets, including Caixin and Sanlian Lifeweek, have published unusually in-depth and critical reports, there are still lines they cannot cross.

By contrast, state media outlets have stuck to the official line and focused on the government’s efforts to tackle the epidemic.

Fu King-wa, an associate professor of journalism at the University of Hong Kong, said transparent reporting was hard to do in mainland China and citizen journalists played an important role in “informing the public and filling a gap that state media cannot fill”.

But by doing so they risk falling foul of the law, which requires reporters to have a press card issued by the General Administration of Press and Publication.

Only those working for registered media can apply for the card and reporters who work without one

risk being punished for illegal reporting under the cybersecurity law.

The Covid-19 outbreak, which is thought to have originated in Wuhan, has so far killed more than 1,500 people and infected more than 66,000.

The authorities put the city in lockdown on January 23 and neighbouring centres in Hubei soon followed suit.

Many Chinese people have gained an insight into what life is like in the cities thanks to ordinary residents sharing videos, pictures or stories on social media.

For instance, one woman known as Xiaohang documented her feelings of despair and helplessness as her parents fell ill and died.

She later fell ill herself, last posting on February 9, and her current condition is unknown.

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But such stories are in stark contrast to the official media’s reporting. For example, on January 23, the day Wuhan went into lockdown, the evening news bulletin from state broadcaster CCTV led with a speech President Xi Jinping gave at a Lunar New Year celebration and devoted less than three minutes of the 50-minute broadcast to the outbreak.

Around a third of that report was devoted to the World Health Organisation’s support for China’s efforts in fighting the outbreak.

The Australia-based political artist and dissident Badiucao said Chinese state media was notorious for only portraying the positive aspects whenever a crisis hit.

“Whenever something tragic happens, they turn it into a celebration of heroes and heroines … Everyone seems happy that China is still strong and can deal with any situation,” he said.

Badiucao has been publishing a series called the Wuhan Diaries, written by a city resident who got in touch with him after a social media appeal for information about life inside the city.

Badiucao said that for safety reasons he did not know any personal information about the author and he had been working with a team of volunteers to translate the diary entries.

The first entry, published on January 27, described panic buying in Wuhan supermarkets. The author also criticised the central government for its handling of the outbreak.

The author noted that officials from Wuhan and Hubei had been the main focus of criticism, but wrote: “I see it differently! Are they the only ones who shall take responsibility!”

Badiucao said that if more people became citizen journalists the risk would be more widely shared.

“We need more people to serve as citizen journalists,” he said. “A lot of journalists in China, young journalists, are risking their lives in Wuhan by reporting on the front line. But they face restrictions. Citizen journalists complement those reporters.”

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But while citizen journalists can share valuable information, there is also a danger that they will help spread misinformation.

Hong Kong University’s Fu said the nature of social media meant that any content uploaded online, verified or not, could spread quickly and widely.

“If they do not do the job well, that could be dangerous because people trust them. They could post something and delete it, but the content would remain in the public domain,” he said.

Badiucao agreed that this was a risk, but said it was unavoidable given the tight controls on information in mainland China.

He pointed out that the author of the diary was “locked in this information black hole as well”.

“All the author can see or hear is the other people who are in similar conditions. So there must be misinformation, misunderstanding of the information,” he said.

“But the diary, it is a kind of an internal reflection that is really loyal to the feeling of how life is inside there.”