Wong was arrested upon reporting to the semi-autonomous city's central police station at 1 pm (0500 GMT) on Thursday, the tweet said.
"The arrest is related to participating in an unauthorized assembly on [October 5] last year," it said.
Wong was told that he violated "the draconian anti-mask law," according to the post, in reference to a ban on face coverings at protests which was ruled particially unconstituational by the city's Court of Appeal late last year.
Avery Ng, chairman of the League of Social Democrats, confirmed that both Wong and Koo Sze Yiu, a fellow member of the group, have been arrested.
Huge anti-government demonstrations broke out in Hong Kong in June 2019 in response to a now-scrapped extradition bill, which would have allowed dissidents to face trial in mainland Chinese courts.
However, last month Beijing introduced a sweeping national security law which essentially put a stop to the protests and permits extradition to China.
Under the national security law, which critics have decried as a crackdown on dissent, secession, subversion, terrorism and collusion with foreign forces can be pu
"The arrest is related to participating in an unauthorized assembly on [October 5] last year," it said.
Wong was told that he violated "the draconian anti-mask law," according to the post, in reference to a ban on face coverings at protests which was ruled particially unconstituational by the city's Court of Appeal late last year.
Avery Ng, chairman of the League of Social Democrats, confirmed that both Wong and Koo Sze Yiu, a fellow member of the group, have been arrested.
Huge anti-government demonstrations broke out in Hong Kong in June 2019 in response to a now-scrapped extradition bill, which would have allowed dissidents to face trial in mainland Chinese courts.
However, last month Beijing introduced a sweeping national security law which essentially put a stop to the protests and permits extradition to China.
Under the national security law, which critics have decried as a crackdown on dissent, secession, subversion, terrorism and collusion with foreign forces can be pu