National identity should never be abandoned no matter how society develops or how individuality prevails because patriotism always involves a higher value of life, a leading official of Beijing's top representative body in Hong Kong said on Wednesday.

Lu Xinning, deputy director of the Liaison Office of the Central People's Government in the Hong Kong Special Administrative Region, made the remark when addressing a ceremony in celebration of the 70th anniversary of the People's Republic of China, noting that Hong Kong is facing the "severest situation" since its return to the motherland.

Lu's call came at a time when some local protesters waved national flags of Great Britain and the United States during recent demonstrations while defiling the national flags of their own.

She said the patriotic spirit of the country's founders should have a place in the fast-changing society, however much the freedom of expression is valued.

Hong Kong people share the same developmental interests and cultural affiliation as their mainland compatriots, Lu said. She appealed to the city's youths to calm down and reflect on how to build a better city and a better country together.

The past two months have witnessed tens of thousands of young people taking to the streets in opposition to the government's handling of a now-suspended extradition bill. Hundreds of them were arrested for their involvement in violent demonstrations, according to Hong Kong police.

Experts have suggested that the lack of proper national education is to blame. Since 2007, the Hong Kong government has sought to introduce national education courses to strengthen students' "national identity awareness", but this attempt drew wide public opposition and was withdrawn.

Lu said she understood that young people love freedom. However, the freedom Hong Kong people pursue should not include the freedom of bullying and destroying, she said.

She cited a recent incident of online bullying of local police officers and their families, as well as vandalism to public facilities and private properties seen during protests.

Lu reiterated the central government's support for the HKSAR government and the police to bring back peace and order, following the chief executive's appeal for a dialogue platform to find a way out of the political impasse.

Chief Executive Carrie Lam Cheng Yuet-ngor, who also attended the ceremony on Wednesday, said the government will resolutely safeguard "one country, two systems" and the rule of law in the event of escalating violence in protests.

She stressed the SAR government has the confidence to restore law and order.

Separately, the city's police force also appealed to the Hong Kong public to stand firm against violence. "These radical protesters are tearing our society apart, and tearing down our core values, including rule of law," said Tse Chun-chung, chief superintendent of the police public relations branch.

It would be hard to imagine how society will turn out if the situation continues unchecked, according to Tse, who added that the rioters' acts can be best described as "reckless and ruthless".