Extensive searches on the Internet in China for the identity of a mysterious protester in the capital, Beijing, criticized China's policy to combat the spread of the Corona virus and President Xi Jinping.

A demonstrator climbed the Sitong Bridge in Beijing's Haidian District, and held two large banners calling for an end to China's COVID-19 policy and the overthrow of President Xi.

Pictures and videos of Thursday's event circulated widely across the internet, prompting a swift crackdown by censors on social media platforms and the WeChat app used by most Chinese.

Thursday's protest came on the eve of the historic Communist Party congress, at which President Xi is due to receive a third term as party chief.

Online investigators have tried to track down the person, focusing on a Chinese researcher and physicist who hails from a village in the northern Heilongjiang Province. A BBC research with village officials confirmed that a man with that name was living there.

What appeared to be an official statement was posted on the popular search site ResearchGate, and it was later deleted, although others have uploaded copies of it.

In the 23-page document, he called for strikes and civil disobedience - such as the smashing of Covid testing stations - on Sunday. This was to prevent "dictator Xi Jinping from continuing in office illegally, so that China could embark on the path of democracy and freedom," according to the document.

The man's name is among the materials related to the protest that has been blocked on the Internet. As of Friday morning, no references to the incident had been found on the Chinese social networking site Weibo.

Protest footage and photos and related keywords including "Haidian", "Beijing protester" and "Sitong Bridge" have been removed.

Although the Chinese media did not mention the incident, former Global Times editor Hu Xijin appeared to be referring to it when he tweeted Thursday evening that the "vast majority" of the Chinese people support Communist Party rule, and that they "hope for stability and oppose unrest." .