Taking to Twitter, US Secretary of State Mike Pompeo said: "Arrests of pro-democracy activists in Hong Kong are deeply concerning - politicized law enforcement is inconsistent with universal values of freedom of expression, association, and peaceful assembly."
Hong Kong law enforcement agency made the arrest on Saturday in connection with the mass protests that rocked Asia's financial hub last year.
According to Al Jazeera, among those arrested was media tycoon Jimmy Lai, founder of anti-establishment tabloid Apple Daily. He was arrested at his home, according to local media reports.
Former legislators 81-year-old Martin Lee, Albert Ho, Leung Kwok-hung and Au Nok-hin were also are accused of orgsing and taking part in unlawful assemblies in August and October.
The raids mark the biggest crackdown by the authorities on the pro-democracy movement since the outbreak of large and sometimes violent anti-government protests.
( With inputs from ANI )