Hong Kong Chief Executive John Lee Ka-chiu on Thursday used a solemn National Constitution Day seminar to mourn victims of a devastating public housing fire that killed at least 159 people, urging residents to vote in Sunday's legislative election to help rebuild the city.

The half-day event, co-hosted by the Hong Kong Special Administrative Region government and the Liaison Office of the Central People's Government in the HKSAR, began with a moment of silence for victims of the blaze that tore through Wang Fuk Court in Tai Po on Nov 26. The traditional applause session was canceled out of respect for the deceased.

"The fire has caused immense casualties. All of Hong Kong society is in extreme grief," Lee said, extending condolences to the bereaved families and survivors left homeless.

Lee on Tuesday announced the establishment of an independent committee to conduct a comprehensive and in-depth review to reform the building work system and prevent similar tragedies from occurring in the future.

"The tragedy has only strengthened my belief in the spirit of the Constitution and the rule of law," Lee told the audience.

He said the Constitution's core purpose is to protect people's well-being and that the government would turn the "painful lessons" into concrete measures to make the city safer.

With the Legislative Council election set for Sunday, Lee made an appeal for high voter turnout, saying capable lawmakers were needed as partners to approve funding, pass new laws and drive systemic reforms in the wake of the fire.

Liu Guangyuan, deputy director of the Liaison Office of the Central People's Government in the HKSAR, echoed Lee's remarks, praising the Hong Kong government's response and stating that holding the election on schedule "conforms with the spirit of the Constitution and rule of law" and would aid post-disaster reconstruction.

He warned that "anti-China destabilizing forces" attempting to exploit the tragedy would "face severe legal consequences".

China's 12th National Constitution Day was observed on Thursday, marking the ninth year Hong Kong has held an official seminar since the day was established in 2014. About 900 participants from various sectors of the community attended the seminar.