A member of the student group Scholarism was arrested at the airport on Wednesday morning for alleged involvement in the unrest which rocked Mong Kok this week.
Violent clashes between police and protesters angered over the government’s clearing of street hawkers broke out on Monday night.
Police have confirmed that the man was set to board a plane to leave Hong Kong but did not give further details.
Student activist group Scholarism said in a statement that its member Derek Lam Shun-hin, 22, was arrested at the Hong Kong International Airport en route to Taipei for a planned seven-day trip with his family. He was taken from the border control counter at 9:50am, and told Scholarism that he had been taken away in connection with an investigation.
The group said Lam was in Mong Kok on Monday night to visit street hawkers at 10pm and left at 2:15am early Tuesday morning. It added that Lam did not attack police and was not involved in any violent behaviour.
“Scholarism is angered by the arbitrary arrest by the police, it is shameful that supporting street hawkers will [make people] face the suppression of the regime,” the statement read.
Scholarism said lawyers were unable to reach Lam.
“We demand the police to explain where is Lam Shun-hin, and release him immediately,” the statement added.
More than 120 people were injured, and 63 people between 15 and 70 years old have been arrested as of Wednesday for allegedly participating in an unlawful assembly, assaulting police officers, resisting arrest, obstructing police officers, possessing offensive weapons, taking part in a riot, among other charges.