Hong Kong riot police have swept into several shopping malls, chasing off and arresting anti-government Hong Kong demonstrators who had gathered to press their demands in the peak shopping weekend before Christmas.

In a mall in Yuen Long, close to the China border, hundreds of black-clad protesters marked the five-month anniversary of an attack in a train station by an armed mob wearing white T-shirts which beat up bystanders and protesters with pipes and poles.

Police had been criticised for not responding quickly enough to calls for help, and for not arresting any alleged culprits at the scene.

But they later made several arrests and said the assailants had links to organised criminal gangs, or triads.

The protesters demanded justice for the attack, shouting 'Fight for Freedom' and 'Stand With Hong Kong'.

'The government didn't do anything so far after 5 months ... I deserve an answer, an explanation,' said a 30-year-old clerk surnamed Law.

'Yuen Long is no longer a safe place ... and we all live in white terror when we worry if we will be beaten up when dressed in black.'