BEIJING (AFP) - Police in China's virus epicentre Wuhan acted "inappropriately" by punishing a doctor who blew the whistle on the outbreak that has now killed more than 9,000 worldwide, a Chinese government investigation found on Thursday (March 19).

Dr Li Wenliang, one of a group of doctors in Wuhan who shared posts on social media warning of a Sars-like virus spreading in the city in December, was reprimanded by police for sharing the information and made to sign a statement agreeing not to commit any more "law-breaking actions".

His death from the virus in February prompted a national outpouring of grief as well as anger at the government's handling of the crisis, and bold demands for freedom of speech.

A central government investigation initiated after Dr Li's death found that Wuhan police "acted inappropriately by issuing a disciplinary letter" and took "irregular law enforcement procedures," state broadcaster CCTV reported on Thursday.

The investigators also found that Dr Li's colleagues had repeatedly attempted to resuscitate the 34-year-old before he was declared dead because he was "very young", CCTV said.

State media said his colleagues told investigators, "as long as there was a bit of hope, we were unwilling to give up, at the time there were no other factors".

The central government investigators "suggest" that Wuhan authorities "supervise and rectify the matter", and urged local police to revoke the disciplinary statement issued to Dr Li, according to CCTV.

Beijing has sought to direct criticism over the mishandling of the virus outbreak onto provincial officials, with several of the region's top Communist Party and health officials sacked.

Dr Li's death had initially been reported by state media before their reports were quickly deleted. Wuhan Central Hospital confirmed Dr Li's death only hours later, after saying he was undergoing emergency treatment.

Social media users who immediately took to the Twitter-like Weibo platform in droves to mourn Dr Li - before posts related to his death were scrubbed by censors - had accused hospital authorities of inappropriately attempting to resuscitate him after he had already died.

China reported zero domestic Covid-19 infections for the first time on Thursday, even as nations across the world shut down in a desperate effort to contain the pandemic.

China's central government has sought to distance itself from the origins of the disease, initially by sacking local officials blamed for allowing the virus to spread, and recently by supporting the conspiracy theory that Covid-19 originated in the United States.