Hong Kong police arrested 15activists in raids on Saturday (April 18) on charges of illegal assembly.
It is the biggest crackdown on the city's pro-democracy movement since the outbreak of mass protests last year.
Among those detained in the swoop were prominent figures in the movement, including millionaire publishing tycoon Jimmy Lai, former legislator and barrister Margaret Ng... ...and Democratic Party Founder Martin Lee, who said he felt relief to be listed as a defendant as many young protesters were detained as well.
It is not known whether those arrested on Saturday were being held in detention.
The marches last year initially targeted a now-scrapped bill proposing to send suspects to mainland China for trial but protests broadened into demands for full democracy and a public investigation of the use of force by police.
Authorities in Hong Kong have arrested more than 7,800 people over their involvement in the protests, including many on rioting charges that can carry jail terms of up to 10 years.
It is not clear how many of them are in custody.