Hong Kong: A major pro-democracy march planned for Saturday in Hong Kong has been cancelled, after three prominent pro-democracy activists were arrested on Friday.

Activists Joshua Wong and Agnes Chow were detained a day after Andy Chan was stopped from boarding a flight, as authorities looked to undercut the momentum of the pro-democracy movement.

Pro-democracy activist Joshua Wong has been arrested. Credit:AP

The arrests underscore the severity of Hong Kong's biggest political crisis since its handover to Beijing more than two decades ago.

Bonnie Leung of the Civil Human Rights Front said the group had no choice but to cancel the march because of concern for the physical and legal safety of participants. It's unclear if protesters would still gather for any unauthorised demonstration.