Miles Kwan left the Cheung Sha Wan Division police station in a taxi on Monday afternoon, according to an AFP reporter at the scene.

Kwan, 24, was among several people behind a petition over the fire that broke out in a housing estate last Wednesday.

The petition called for government accountability, an independent probe into possible corruption, proper resettlement for residents, and a review of construction oversight.

Local media reported on Saturday that Kwan was arrested for "seditious intention" by national security police, citing unnamed sources.

Police did not confirm the arrest, saying only that they "will take actions according to actual circumstances and in accordance with the law".

Kwan said Friday that he was only "proposing very basic demands".

"If these ideas are deemed seditious or 'crossing the line', then I feel I can't predict the consequences of anything anymore, and I can only do what I truly believe," he told AFP at the time.