Hong Kong police on Wednesday arrested Joshua Wong and Lester Shum, two of the student leaders at the heart of pro-democracy protests that have shaken the Asian financial hub since August, and began swiftly clearing a major demonstration site.

Riot police scuffled with protesters trying to resist attempts to force them off the streets of the gritty Mong Kok district following clashes overnight, witnesses said.

Hundreds of protesters remained on Nathan Road, at the heart of the protest site in Mong Kok, brandishing yellow banners and chanting demands for "full democracy" in the former British colony, but were pushed back by the large number of police. Within about two hours most of the protesters' tents had been removed.