Au Nok-hin and Jeremy Tam were arrested on suspicion of obstructing police, Tam's Civic Party said on its verified Facebook page.
Two more Hong Kong pro-democracy lawmakers were arrested late Friday, the Civic Party said, bringing to three the number of members of the city's parliament targeted in a protest crackdown.
Au Nok-hin and Jeremy Tam were arrested on suspicion of obstructing police, while Au was accused of assaulting a police officer, Tam's Civic Party said on its verified Facebook page.
Earlier in the day, activists Joshua Wong and Agnes Chow were granted bail after being charged with inciting people to join a protest in June, while authorities denied permission for a major march in what appears to be a harder line on this summer's protests.
Police said Wong and Agnes Chow are being investigated for their role in a June 21 unauthorised protest outside a police station. Both are charged with participating in the demonstration and inciting others to join it. Wong is also charged with organising it.
Andy Chan, the leader of a pro-independence movement, was arrested at the airport on Thursday night. Three others were taken in earlier this week for vandalising legislature offices on July 1.
The organisers of the major pro-democracy march planned for Saturday in Hong Kong have called it off after an appeals board denied permission to hold it.
It's unclear if protesters would still gather for any unauthorised demonstration.
Bonnie Leung of the Civil Human Rights Front said on Friday that the group had no choice but to cancel the march because of concern for the physical and legal safety of participants.
Demosisto's vice-chairperson Isaac Cheng urged residents to continue protesting despite a high risk of arrest.
The Demosisto's vice-chairperson said the arrests of two prominent members of the pro-democracy group are an attempt to spread fear and "white terror" among Hong Kong residents.
Cheng spoke to reporters on Friday about the arrests before Saturday's banned rally.
"He was suddenly pushed into a private car on the street,” Wong’s political party Demosisto, which advocates for greater democracy in Hong Kong, said on its official Twitter account.
“He has now been escorted to the police headquarters in Wan Chai,” it said, adding its lawyers were working on the case.
Unrest in Hong Kong escalated in mid-June over a now-suspended extradition bill that would have allowed people to be sent to mainland China for trial in Communist Party-controlled courts.
It has since evolved into calls for greater autonomy under the "one country, two systems" formula, which guarantees freedoms not enjoyed on the mainland, including an independent judiciary.
China rejects withdrawal of extradition bill - reports
Earlier this summer, Carrie Lam, the chief executive of Hong Kong, submitted a report to Beijing that assessed protesters' five key demands and found that withdrawing a contentious extradition bill could help defuse the mounting political crisis in the territory.
The Chinese central government rejected Lam's proposal to withdraw the extradition bill and ordered her not to yield to any of the protesters' other demands at that time, three individuals with direct knowledge of the matter told Reuters.
China's role in directing how Hong Kong handles the protests has been widely assumed, supported by stern statements in state media about the country's sovereignty and protesters' "radical" goals.
The Chinese central government has condemned the protests and accused foreign powers of fuelling unrest. The Foreign Ministry has repeatedly warned other nations against interfering in Hong Kong, reiterating that the situation there is an "internal affair."
Police will ban mass rally and march on Saturday to call for universal suffrage on fifth anniversary of failed Hong Kong electoral reform package, sources revealhttps://t.co/mudhcHxuI3— Joshua Wong 黃之鋒 (@joshuawongcf) August 28, 2019
On Thursday, China brought fresh troops into Hong Kong in what it described as a routine rotation of the garrison.
Chinese state media stressed the troop movement was routine and Asian and Western diplomats watching the People's Liberation Army (PLA) forces in the former British colony had been expecting it.
Chinese soldiers stationed in Hong Kong are not there merely for symbolic purposes and they will have "no reason to sit on their hands" if the situation in the city worsens, an editorial in the China Daily newspaper said on Friday.
Police have refused permission for an anti-Beijing march on Saturday, but organisers had appealed against the decision.
The protest would mark five years since Beijing ruled out universal suffrage for Hong Kong and comes as Hong Kong faces its first recession in a decade, with all its pillars of growth under stress.