Lam Cheuk-ting, Ted Hui and at least 14 others have been detained over protests last year, triggered by the government's decision to pass an extradition bill allowing suspects to be sent to mainland China to stand trial.
Two prominent Hong Kong opposition lawmakers have been arrested along with more than a dozen others in a police operation focused on last year's anti-government protests, part of a widening crackdown against the city's democracy camp.
Lam Cheuk-ting and Ted Hui were detained on Wednesday after early-morning raids on their homes, according to their political party and the police.
Opposition figures decried the arrests, which add to a mounting toll of prosecutions targeting Beijing's critics in the restless financial hub.
"This is out-and-out political persecution," James To, a veteran lawyer and member of the Democratic Party, told reporters after the arrests.
Lam, Hui and at least 14 other — aged between 26 and 48 years old — were arrested during Wednesday's operation, which focused on protests in July last year.
Both are minority anti-Beijing lawmakers in the city's partially elected legislature and vocal critics of both Beijing and the Hong Kong government.
A post on Lam's Facebook page said he was arrested "on suspicion of participating in rioting on July 21" last year.
That day, Lam and dozens of anti-Beijing protesters were beaten by a gang of government supporters, some with "triad" organised crime links, in the town of Yuen Long.
Police were late to arrive on the scene and were also filmed allowing some of the armed attackers to leave – scenes that sent already swirling distrust of the force skyrocketing and helped fuel further months of protests.
Lam was also charged with "conspiring to damage property and obstruction of justice outside Tuen Mun police station on July 6 last year", the statement said.
Hui's office released video footage of his arrest where officers said they were charging him with attempted obstruction of justice, access to a computer with criminal or dishonest intent and criminal damage.
He was later led from his house in handcuffs. The party said his charges also stemmed from a protest on July 6 last year.
Police said a press conference would be held later in the day.
Hong Kong was hit by seven straight months of massive and often violent anti-Beijing protests in 2019 in which more than 9,000 people were arrested.
The popular unrest upended the city's reputation for stability and sparked a crackdown by China that has gathered pace this year.
In late June, Beijing imposed a sweeping new security law, tightening Communist Party control over the semi-autonomous city and ending the legal firewall between the two territories.
Certain political views such as advocating independence or greater autonomy for Hong Kong became illegal overnight and arrests have followed.
In response to the law, many Western nations ended extradition agreements with Hong Kong.
The United States has placed sanctions on some Chinese and Hong Kong officials and declared the business hub no longer sufficiently autonomous from the authoritarian mainland.
The anti- Beijing protests died down at the start of 2020 thanks to mass arrests and anti-coronavirus restrictions.
City leader Carrie Lam began the year vowing to heal divisions.
But police have since arrested dozens of prominent anti-Bejing figures on a slew of charges related to the rallies, with the courts now filled with hearings and trials.
Authorities have denied allegations the investigations are politically motivated.
Wu Chi-wai, chairman of the Democratic Party, said the latest arrests would do little to heal divisions.
"The government is wielding the legal system and the police force to suppress dissenting voices within society and create a chilling effect instead of trying to reconcile confrontation and polarisation," he said.