Beijing authorities removed rare banners of political protest from an overpass in the Chinese capital, according to images circulated widely on social media on Thursday, just days before the start of a twice-in-a-decade Communist Party congress.

The banners bore several slogans, including a call for President Xi Jinping’s ouster and an end to strict Covid-19 policies, according to numerous images and videos circulated on Twitter, which is blocked in China.

Smoke could be seen emanating from the roadway above where the banners were hung in Beijing’s northwestern Haidian district, according to the images.

Haidian is home to several prestigious universities.

The incident comes at a very sensitive time in the Chinese capital, with authorities on high alert in the run-up to the 20th congress of the ruling Communist Party, where Xi is expected to secure a third leadership term.

“Let us strike from schools and from work and remove the dictatorial traitor Xi Jinping,” one of the slogans read.

It is highly unusual for Xi to be specifically named in protests in China, where residents use euphemisms and oblique phrasing and images in efforts to evade censorship.

“We don’t want Covid tests, we want to eat; we don’t want lockdowns, we want to be free,” another message on the red-lettered banners read.

China’s zero-Covid policy, which has led to frequent lockdowns and caused economic damage, has fuelled frustration in Chinese cities.

There was a noticeable police presence in the area on Thursday evening, with several police cars and officers standing watch at the thoroughfare where the banners had been hung.

There were no traces of the banners or of fire.

Beijing police and the municipal government did not immediately respond to requests for comment sent to their official WeChat accounts.

Search terms related to the pictures and the protest topic yielded no results on China’s heavily censored Internet, although multiple indirect references could be found.

“There was a brave person in Beijing today,” one Chinese social media user wrote.

Others showed support on the WeChat app by sharing links to a formerly little-known song called Sitong Bridge — the name of the Haidian bridge — by an artist called Biuya.

By early evening, the song was censored on various Chinese music apps. Hu Xijin, the former editor of China’s Global Times tabloid and a high-profile commentator, tweeted: “China is currently stable, especially it’s capital Beijing. The Covid19 epidemic has been well-controlled here. In Beijing there is no public dissatisfaction caused by epidemic control as in some other places in China.”