The arrest comes after China imposed a sweeping new national security law on Hong Kong in late June.
Hong Kong police have arrested prominent democracy activist Joshua Wong for participating in an unauthorised assembly in October 2019 and violating the city's anti-mask law, according to a post on his official Twitter account.
Wong's latest arrest adds to several unlawful assembly charges or suspected offences he and other activists are facing related to last year's pro-democracy protests, which prompted Beijing to impose a sweeping national security law on June 30.
Hong Kong police confirmed they arrested two men, aged 23 and 74, on Thursday for illegal assembly on October 5, 2019.
#BREAKING Joshua is arrested when reporting to Central Police Station at about 1pm today. The arrest is related to participating in an unauthorized assembly on 5Oct last year. He is told to have violated the draconian anti-mask law as well.— Joshua Wong 黃之鋒 😷 (@joshuawongcf) September 24, 2020
UK voices concern
Britain, which administered Hong Kong until a 1997 handover to China, whose terms were agreed in a Joint Declaration between London and Beijing, expressed concern over Wong's arrest.
"I am deeply concerned about the arrest of Joshua Wong, another example of HK authorities targeting activists," Foreign Secretary Dominic Raab said in a Tweet.
"Chinese and HK authorities must respect the rights and freedoms of the people of Hong Kong, as protected in the Joint Declaration," he said.
READ MORE: Protesters in Hong Kong rally against postponed elections and security law
I am deeply concerned about the arrest of Joshua Wong, another example of HK authorities targeting activists. Chinese and HK authorities must respect the rights and freedoms of the people of Hong Kong, as protected in the Joint Declaration.— Dominic Raab (@DominicRaab) September 24, 2020
The arrest of Wong, aged 23, comes around 6 weeks after media tycoon Jimmy Lai was detained on suspicion of colluding with foreign forces.
Wong had been a frequent visitor to Washington where he appealed to the US Congress to support Hong Kong's democracy movement and counter Beijing's tightening grip over the global financial hub. His visits drew the wrath of Beijing, which says he is a "black hand" of foreign forces.
Wong disbanded his pro-democracy group Demosisto in June, just hours after China's parliament passed a national security law for Hong Kong, bypassing the city's local legislature, a move widely criticised by Western governments.
Fame after umbrella movement
His long-time colleague, Agnes Chow, and two other activists were also among 10 people police arrested in August on suspicion of violating the new law.
The new law punishes, with up to life in prison, for anything China considers subversion, secession, terrorism or collusion with foreign forces.
Wong was just 17 years old when he became the face of the 2014 student-led Umbrella Movement democracy protests, but he was not a leading figure of the often violent unrest that shook the semi-autonomous former British colony last year.
An anti-mask law, introduced last year in a bid to help police identify the protesters they suspected of committing crimes, is facing a challenge in court. The Hong Kong government has made face masks mandatory in most circumstances due to the coronavirus pandemic.
READ MORE: Hong Kong arrests opposition lawmakers over 2019 protests