Hong Kong police arrested more than 250 people in Mong Kok on Sunday night following a day of anti-government protests across the city.

A source said about 200 of those were detained on suspicion of unlawful assembly. Earlier in the day, hundreds of protesters gathered in at least 10 shopping malls to chant slogans and sing Glory to Hong Kong, the anthem of the anti-government movement .

Police said they arrested one man who had materials capable of making petrol bombs.

In the evening, a small group of protesters in the busy Mong Kok shopping district attempted to block roads by setting trash and rubbish bins on fire but were quickly dispersed by police.

Officers in riot gear then took up guard on the street, firing pepper spray on a number of occasions, including twice at reporters, and taking away several people.

Democratic Party legislator Roy Kwong Chun-yu, who turned up in Mong Kok to negotiate with police, was subdued by several officers as he crossed a street, with one pressing his knee onto the politician�s head. The party wrote on its Facebook page that Kwong was to be charged with disorderly behaviour and brought to Hung Hom Police Station. Earlier, protesters circulated messages online, urging people to gather in malls by 3pm. The shopping centres included Harbour City in Tsim Sha Tsui, Cityplaza in Taikoo Shing and Moko Mall in Mong Kok. Since April 26, when hundreds gathered in Cityplaza to chant slogans, Hong Kong has seen a revival of protests, which had died down because of the Covid-19 pandemic .

The protesters had earlier planned a march from Tsim Sha Tsui to Mong Kok demanding the resignation of Hong Kong�s embattled leader Carrie Lam Cheng Yuet-ngor. But the event was postponed indefinitely after police objected on the grounds of restrictions on public gatherings to curb the spread of the virus.

In Tsim Sha Tsui, dozens of officers had been on patrol from the early afternoon. At least a dozen people were searched and two were taken to police vehicles. At about 3pm, a crowd of people, including some with placards, gathered on the steps leading to Harbour City. The crowd retreated into the mall after officers marched towards the building, but police did not initially enter the mall and protesters continued to chant slogans.

Shortly after 4pm, police entered the shopping centre, saying there was a public gathering of more than eight people inside. A few people were stopped inside as police cordoned off parts of the mall.

Among those taken away was a 12-year-old boy who claimed to be a student reporter. He was later released after police warned his mother against allowing him to take part in �illegal child labour�.

The boy said: �Police asked me twice if I was working as an illegal child worker, but I explained I was only a volunteer.�

The boy said he was volunteering for Student Depth Media, a student-run news organisation set up this February. The group also issued a statement on its Facebook page and said the boy was working for it on a voluntary basis, and labour laws did not apply. It also said a 16-year-old girl who worked for the group had been taken away by police too.

In Mong Kok, police armed with non-lethal guns also entered Moko Mall in the afternoon, and fired what was believed to be a pepper ball to disperse protesters.

One man was arrested after officers seized items including petrol, towels and several lighters after intercepting a group of protesters, the force later said on its Facebook page.

Police said they did not rule out the possibility the materials, purportedly for making petrol bombs, would be used, seriously endangering public safety.

Officers also entered other malls and told people to leave.

Earlier in the day, police asked media personnel to disperse from Tsim Sha Tsui, warning that they might be violating the ban on public gatherings of more than eight people, a restriction put in place to help halt the spread of Covid-19. A Post reporter was searched despite showing his press card.

During the search, an officer told him: �Don�t play with your phone, smartphones are fragile these days.�

Another officer filmed the journalist after he was asked to remove his mask. He was later let go.

Among the crowd at Harbour City was a family of four celebrating Mother�s Day.

The mother said she was not aware a protest was planned but it did not affect her. �I explained to my daughters what [the protesters] were trying to say,� she said.

A 19-year-old student, who did not want to be named, said he expected protests to become more frequent as the coronavirus came under control locally.

�With or without the ban, people will come out, and those who are out are prepared to be arrested,� he said.

Some shops at Harbour City closed early, but others served customers with shutters closed.

In a statement, a police spokesman said protesters had gathered in various shopping malls across the city, holding banners, shouting slogans and undermining public order.

�Police received reports from the public and entered the malls to enforce the law,� he added, noting that gatherings of more than eight people in public places were prohibited. Protests first broke out in June last year, sparked by a now-withdrawn extradition bill. The demonstrations later evolved into a wider anti-government movement, with clashes between radical protesters and police turning increasingly violent. With the onset of the coronavirus crisis, the campaign began losing momentum.