At least four people were injured by a blade-wielding man who rampaged through a mall in Hong Kong as riot police stormed shopping centres in a move to block protesters from staging rallies.

The bloody attack took place amid a day of chaos in Hong Kong that also saw an elected local councillor have part of his left ear bitten off.

Pro-democracy activists called a spate of flashmobs in shopping centers on Sunday in a bid to keep up the momentum of the protest movement that has swept the city with violent clashes for five months.

The actions came after a day of running battles on Saturday, and riot police stormed several malls early the day in an attempt to stop the rallies from taking place.

Officers stationed at planned protest sites blocked certain areas, dispersed crowds and made arrests. Nonetheless, protesters succeeded in worming their way into malls in several neighbourhoods, forming a human chain, chanting slogans, and blocking entrances to prevent police officers from entering.