An anti-Hong Kong democracy rally turned ugly in Sydney's CBD on Saturday, with protesters shouting jingoistic slogans and two men escorted away under police protection after they were confronted by rally attendees.

The protesters, most of them believed to be migrants from mainland China, attended the rally to support Beijing’s policies in Hong Kong. The group gathered at Belmore Park about noon and marched to Sydney Town Hall, chanting "long live China", with attendance estimates varying from 200 to 3000.

An anti-democracy protester grabs a man with a Taiwanese man around the neck at a rally in Sydney. Credit:AAP

During the protest, an elderly man holding a sign supporting freedom in Hong Kong was escorted away by police after being surrounded and verbally abused by mainland protesters. "He’s being protected by the police, otherwise we’d beat him to death," a woman said in Mandarin as others cursed at him "Traitor! Traitor!"

A man holding a Taiwanese flag was confronted by rally attendees at the tail end of the event and appeared to be grabbed around the neck by another man before he fell to the ground. Police later broke up the fracas and escorted the man to safety.