The death of a whistleblowing Chinese doctor who was punished for trying to raise the alarm about coronavirus has sparked an explosion of anger, grief and demands for freedom of speech among ordinary Chinese.

Li Wenliang, 34, died in the early hours of Friday local time after he was infected during the fight against the outbreak, said Wuhan central hospital, where he worked, in a statement.

Li warned colleagues on social media in late December about a mysterious virus that would become the coronavirus epidemic and was detained by police in Wuhan on 3 January for “spreading false rumours”. He was forced to sign a police document to admit he had breached the law and had “seriously disrupted social order.”

“They owe you an apology, we owe you our gratitude. Take care, Dr Li,” said a Weibo post from Xiakedao, an account under the overseas edition of Communist Party’s People’s Daily.

“Good people don’t live long, but evil lives for a thousand years,” said another post mourning Li’s death, with a candle emoji. An image also posted on Weibo showed a message, “farewell Li Wenliang”, carved into the snow on a riverbank in Beijing.

His death crystallised the outrage and frustration felt across China over the initial cover-up of the deadly virus. On Friday, China’s social media was awash with posts expressing immense anger and grief.

Li’s death became the top-read topic on China’s microblogging site Weibo overnight on Friday, with more than 1.5bn views, and was also heavily discussed in private WeChat messaging groups, where people expressed outrage and sadness.

Even blog posts from state media outlets mourned his death and issued veiled attacks on the Wuhan authorities who censured him.

The strong public reaction appeared to have drawn the top leadership’s attention. The central commission for discipline inspection, the Communist party’s powerful internal anti-corruption body, and the national supervisory commission, the country’s highest anti-corruption agency, issued a one-sentence statement on their joint website that investigators will be sent to Wuhan to carry out “a comprehensive investigation into the problems reported by the public concerning Doctor Li Wenliang”.

Fearing that the uproar over Li’s death could spill over onto the streets, the authorities quickly deleted posts calling for action. A post forwarded on Wechat but now deleted said: “I hope one day we can stand on the street holding Li Wenliang’s picture.”

In Li’s last blog post on Weibo, China’s Twitter-like microblog, on 1 February, Li poignantly wrote: “The test results come out positive today. Everything is settled. It is confirmed.”

Li was one of eight people who were detained for “spreading rumours” about the deadly disease’s outbreak – the fates of the other seven, also believed to be medical professionals, are not known.

Images of Li were ubiquitous on Weibo and messaging app WeChat; a last photo of him lying on his hospital bed wearing a breathing mask; a pencil sketch of Li; a photo of the humiliating police warning document on which he signed “I understand” to admit “spreading false rumours” along with images of candles and white flower.

Many posts referenced his “confession”, with people posting photos of themselves wearing surgical masks emblazoned with the words: “I don’t understand”. Others swore “We will not forget”.

The outpouring of grief quickly turned into demands for freedom of speech, but those posts were swiftly censored by China’s cyber police. The trending topic “#we want freedom of speech” had nearly 2m views on Weibo by 5am local time, but was later deleted. The phrase “#Wuhan government owes Dr Li Wenliang an apology” also attracted tens of thousands of views before it too disappeared.

Caixin, a Beijing-based financial publication, posted a black-and-white selfie of Li wearing a mask with the title “A healthy society shouldn’t have just just one voice: Novel Coronavirus whistleblower Li Wenliang dies”.

In its Weibo post, the Economic Observer, a state-affiliated financial newspaper, demanded the vindication of all of the Wuhan “rumour mongers”.

“Dr Li is telling us [through his death] what kind of future we will face if we lose the ability to express ourselves. In the eyes of the people, Dr Li was the hero who bravely told the truth,” the post said. “Wuhan [authorities] should vindicate them and pursue those who abused their powers to suppress the ‘rumour mongers’.”

Elsewhere, posts from ordinary Chinese people continue to direct their outrage towards the authorities.

“You and I both know that the ones who killed were not bats,” said one. “The virus has infiltrated those people high up,” said another. “Those who won’t let you speak won’t let you live either,” fumed another.

Johnny Lau, a veteran China watcher and former journalist at Beijing-backed Wen Wei Po, said Li’s death has become an emotional flashpoint amid the tight control of speech under Xi Jinping’s rule.

“Here is a doctor with a conscience … people on the frontline have been sacrificed but the officials have not been held to account,” he said. “It is an example of how evil has triumphed over the good.” He said the quick deletion of posts demanding speech freedom has aroused further anger.

“The authorities are anxious that his death would trigger a huge wave of anger, so felt the need to maintain stability and suppress people’s voices,” he said. “But this has aroused further pushback.”

Sarah Cook, a senior research analyst and China Media Bulletin Director at Freedom House, said the public outcry over Li looked “widespread and unified”, but it still unclear how big a turning point it could be.

As many inside China seethed, the death toll inside the country passed 630, with more then 31,000 people infected. Another 41 people on a cruise ship quarantined off Yokohama in Japan tested positive for the virus.

Australia became the latest country to advise any citizens inside China to leave as soon as possible. On Friday, North Korea recorded its first confirmed case of the virus.

Additional reporting by Lily Kuo, Jiahui Huang and Reuters