Police said 53 people had been arrested for unlawful assembly, disorderly conduct and other charges. They said protesters blocked roads repeatedly and build barricades with traffic cones and other objects. Some protesters were also stopped and searched by police.
"Lawful protests are always respected but unlawful acts are to be rejected. Please stop breaking the law," police said in a tweet.
It was the one-year anniversary of a huge march through central Hong Kong that grew into a pro-democracy movement that saw protesters break into the legislative building and take to the streets every weekend for months.
"The mass protest on last year has been etched in the collective memory of Hongkongers," the Civil Human Rights Front, which organised the event, wrote in a Facebook post. "It also marks the beginning of our togetherness in defending our beloved city."
Protesters also gathered in shopping centres to mark the anniversary, holding up signs and banners reading "Liberate Hong Kong" and singing protest songs.
The June 9, 2019, local time march was in opposition to a proposed extradition bill that would have allowed people in the former British colony, which has its own legal system, to be sent to mainland China to face trial. Organisers pegged the turnout at more than a million people, while police estimated the crowd at 240,000.
In the ensuing months of protests, violent clashes broke out at times between protesters and the police, leading to accusations of police brutality and sparking protester demands for an independent inquiry into police behaviour.
There was a lull in protests during the coronavirus outbreak early this year, but as infections have ebbed, protesters have returned to the streets to demonstrate against an imminent national security law for Hong Kong as well as a recently approved law that makes it illegal to insult the Chinese national anthem.
Critics and protesters say the national security law is a blow to the "one country, two systems" framework following the handover of Hong Kong from Britain to China in 1997, which promised the city freedoms not found on the mainland.
China blames the protests in part on foreign intervention and is hastening to enact the national security law aimed at curbing secessionist and subversive activities in Hong Kong.
- AP