Pan-democrats have launched a bid in the legislature to remove Hong Kong’s leader from office, accusing her of making “many unconstitutional decisions” in pushing forward the highly unpopular extradition bill and handling the months-long social unrest.

The motion against Chief Executive Carrie Lam Cheng Yuet-ngor, launched under Article 79 of the Basic Law, the city’s mini-constitution, was tabled by Civic Party leader Alvin Yeung with the support of 24 other pro-democracy camp lawmakers during a full council meeting.

The motion says Lam has committed “serious breaches of law” or “dereliction of duty” in her handling of both the now-withdrawn extradition bill and the social unrest it sparked.

No vote was passed as the meeting closed at 7.30pm. The debate will continue on Thursday.

“The chief executive who brought this disaster to Hong Kong should immediately resign,” Yeung said.

In his speech, Yeung said Hongkongers had voiced their dissatisfaction with Lam and her government in the recent district council polls.

The city’s pro-government camp suffered a major setback in the November 24 elections, as it only managed to secure some 60 of 452 seats in the district councils. Pan-democrats won control of 17 of the city’s 18 councils.

The motion, which requires a majority support from both the Legco’s geographical and functional constituencies, is unlikely to pass without the support of the pro-Beijing camp, which controls both constituencies.

Pro-government lawmakers had been filibustering to block the motion from being tabled before the November 24 polls, to avoid having to vote down the motion, which could have cost them the support of the middle-ground voters.

In the motion, pan-democrats argued that Lam’s administration had used excessive force against peaceful protests since June, intimidating protesters with disproportionate criminal charges, “causing a rift in society”, and violating the public’s freedom of expression and assembly as stated in the Basic Law.

Protesters had been seriously hurt during clearance operations, and some were blinded by projectiles fired by police, the lawmakers noted.

Should the motion pass, the Chief Justice will form and chair an independent investigation committee to look into charges against Lam.

In case the committee finds enough evidence to substantiate the charges, lawmakers will vote again.

If two-thirds of 69 sitting lawmakers support removing Lam, the Basic Law stipulates that the results will have to be reported to the central government “for a decision”.

Representing the government, Chief Secretary Matthew Cheung Kin-chung acknowledged the administration’s performance could be improved, but rejected the notion that Lam should step down.

“The chief executive’s every decision has been lawful and constitutional, she did not break the law or commit dereliction of duty,” Cheung said.

Cheung said the continuing protests had gone beyond the extradition bill, and he assailed radical protesters who vandalised train stations and attacked police as well as people with different political views.

Since June, when the mass protests began, Lam’s popularity has plunged to historic lows.

Polls conducted by the Hong Kong Public Opinion Research Institute put Lam’s support rating at 19.7 last month from 43.3 in June.

The lowest rating seen earlier was for Hong Kong’s first chief executive, Tung Chee-hwa, at 36.2.