Police dispersed anti-government protesters and detained dozens of them on Friday as hundreds defied a health ban against large gatherings in locations across Hong Kong to mark the June 12 anniversary of the first major clashes that launched last year’s social unrest.

Ignoring social-distancing rules for Covid-19, demonstrators hit the streets at night in districts, including Causeway Bay, Sha Tin, Mong Kok, Tai Po, Yuen Long and Kwun Tong, despite police warning they risked arrest for unauthorised assembly and could face five years in jail.

On June 12 last year, trouble flared outside the Legislative Council after tens of thousands gathered there to demand the withdrawal of an extradition bill that would have allowed fugitives to be sent to the mainland and other jurisdictions with which Hong Kong has no transfer arrangement.

The clashes marked a turning point for the movement, and the unrest has not died down even after the withdrawal of the bill.

The “very hot” weather warning was in place, and the Observatory also issued the typhoon standby signal No 1 for the first time this year, as hundreds of protesters gathered on the streets. They sang the anthem of the protest movement, Glory to Hong Kong, and chanted slogans.

Officers in riot gear were out in force, and police confirmed that a male suspect was arrested for allegedly attacking a man with a knife in Kwun Tong. Police said the suspect had been shouting at people gathered at a protesters’ street booth before the incident.

Police said that as of 10pm, 35 people – 24 men and 11 women – had been arrested for offences including wounding, participating in an unauthorised assembly, misconduct in a public place, and possession of offensive weapons.

In Causeway Bay, police officers raised a blue flag shortly after 8pm, warning protesters to disperse. Officers then charged at protesters multiple times and pinned down several of them outside the Island Beverley shopping mall. Among those arrested in Causeway Bay was opposition lawmaker Ted Hui Chi-fung.

Police urged protesters in Causeway Bay to disperse, warning that anyone who took part in illegal assemblies might breach the Public Order Ordinance. They also warned of the risk of Covid-19 and cited the ban on groups of more than eight people.

A woman said she was pepper-sprayed when officers dispersed the crowd on Lockhart Road at around 9pm. Police media liaison officers were later seen helping her rinse her eyes.

Other witnesses also said they had seen police use the crowd-control agent. An hour later, another group of protesters was pepper-sprayed, and a reporter among the crowd was later taken to hospital by ambulance.

Despite repeated warnings that they were breaching the Public Order Ordinance and the Covid-19 social-distancing rules, protesters were still in the area after 10pm. Police also subdued a man outside the MTR exit on Great George Street and pepper-sprayed the surrounding crowd.

Physical education teacher Katrina Kwok, 53, said: “In the last year, Hong Kong went from a city full of freedom to one without any. Although the [protesting] students weren’t able to get many results despite their efforts I still want to support them by turning up on the streets to protest.”

Across the harbour, the Langham Place shopping centre in Mong Kok was heavily guarded by riot police, who stopped and searched some masked youngsters. A group of protesters gathered there were chanting familiar slogans such as, “Hong Kong independence, the only way out,” “Hongkongers build a nation!” and “Disband Hong Kong police now.”

Hundreds also sang the protest anthem outside the nearby Grand Plaza at 8pm. Riot police raised a blue flag there as well. Around Nathan Road, a main thoroughfare, police warned those shouting abusive slogans that they were breaching the peace and would be arrested.

Dressed in school uniform, Form Five students Tiffany Lam, 16, and Jenny Tsoi, 18, were among the protesters. Lam said she had skipped a school exam on June 12 last year to join protests. But one year on, she felt the fight was getting harder with the national security law coming soon.

“There are also fewer people coming out in Hong Kong,” Lam said. “I have thought of giving up. It feels like there is not much hope.”

At the New Town Plaza mall in Sha Tin, opposition district councillors had set up boards displaying photos of the anti-government movement. The mall broadcast messages urging people to abide by social-distancing rules.

They greeted the impending arrival of the national security law with open defiance, chanting, “Hong Kong independence, the only way!”

The slogan was once a fringe call but has become more prominent over the past weeks.

In Yuen Long, dozens of protesters sang their anthem and chanted slogans. Riot police officers immediately dispersed a crowd gathering near Yuen Long railway station, warning they would take further action soon.

“Stop gathering here – we are now filming the scene,” one officer in Yuen Long shouted. “Let’s charge everyone who is in an eight-people gathering. I have already issued two warnings [for breaching social-distancing rules],” the officer said, urging his colleagues from the video team “to film everybody”.

One of the protesters in Yuen Long, 32-year-old Marcus Yang, who works in the retail industry, accused police of using the social-distancing ban as a tool to curb freedom of assembly.

“I was taken away and given a penalty ticket just because I shouted ‘rogue cops’. I do not know the two people around me, who were also given the tickets, at all,” he said.

On Friday morning, dozens of pupils from at least six schools defied the education minister’s warnings to mark the June 12 anniversary by forming human chains and chanting slogans.