HONG KONG - Extensive violence once again vindicates the urgent need for a national security legislation in Hong Kong, the special administrative region's (SAR) Secretary for Security John Lee Ka-chiu said in a statement Monday.

Pointing out how some people had displayed banners to advocate Hong Kong independence during Sunday's protest, he was quoted as saying in the statement: "Terrorism is growing in the city and activities which harm national security, such as Hong Kong independence, become more rampant."

"In just a few months, Hong Kong has changed from one of the safest cities in the world to a city shrouded in the shadow of violence," he said in the statement, adding national security laws were needed to safeguard the city's prosperity and stability.

Lee's statement comes as the National People's Congress, the nation's top legislature, is deliberating a draft decision on national security legislation in Hong Kong. The law will outlaw acts of secession, subversion, terrorism and foreign interference in the city.

The Hong Kong government's top officials and lawyer groups in the city have strongly condemned violence during illegal protests Sunday.

Police Commissioner Chris Tang Ping-keung said there have been 14 cases involving explosives "commonly used in terrorist attacks overseas" and five seizures of firearms and ammunition since protests began in June last year. The draft legislation "will help combat the force of 'Hong Kong independence' and restore social order. Police fully support it," Tang said.

Commissioner of Correctional Services Woo Ying-ming, Commissioner of Customs and Excise Hermes Tang Yi-hoi and Controller of the Government Flying Service Captain Wu Wai-hung on Monday also showed their full support for the national security legislation.

On Sunday afternoon, radical protesters staged illegal assemblies in Wan Chai and Causeway Bay districts, smashing shops, vandalizing public facilities and attacking people, including a lawyer. Police made 180 arrests.

According to police, a 40-year-old man had an argument with protesters erecting roadblocks in Causeway Bay. A video clip shows about five radical protesters hitting him with umbrellas and chasing him down as he tried to escape. The man, who left the scene bleeding from his head and with his shirt torn, was taken to a hospital after the incident.

After watching the video clip, Secretary for Justice Teresa Cheng Yeuk-wah described the assault as "shocking" and "distressing". Attacking innocent people or those who hold different views is by no means acceptable, she said. "No one shall resort to violence to solve a problem. Using any unlawful means for any purpose will undermine the rule of law."

The Small and Medium Law Firms Association of Hong Kong said the assault on the lawyer, who is a member of the association, was "outrageous".

In a statement, the association said that "extreme violence will only undermine Hong Kong's rule of law and safety. The Association condemns all acts that endanger national security, public safety, personal safety and the 'one country, two systems' (principle)."

The freedom of expressing concerns is not unlimited. The premise of freedom of speech is complying with the laws, said the association in the statement.

The Law Society of Hong Kong also condemned the attack on lawyer as "outrageous". In a statement on Monday, it iterated that all forms of violence constitute insults to the rule of law, and must be stopped immediately.

Since June last year, Hong Kong has seen escalating violence triggered by a now-withdrawn extradition bill, with a few cases involving possession of explosives and firearms. More than 8,300 people have been arrested so far in connection with protest-related offenses.