Tens of thousands of protesters have gathered in Melbourne’s CBD in the biggest rally yet against Victoria’s contentious pandemic bill and vaccine mandates.

The demonstrators loosely comprise groups who oppose COVID-19 vaccines, mandates and the state’s proposed pandemic laws, which stalled in the upper house this week.

Protesters were watched by police as they chanted “Kill the bill” and carried a range of flags and placards.

A counter demonstration has also attracted a sizeable crowd but the group have pledged not to seek a confrontation as they marched from inner-city Carlton to the CBD.

Organiser Nahui Jimenez said the Campaign Against Racism and Fascism rallies in Melbourne, Sydney, Brisbane and Perth were designed to draw public attention to the “growth of conspiratorial, anti-human and fascistic politics”.

“Hostility to vaccines has become a gateway to the far right globally,” she said.

“We will not allow fascist groups to propagate their bigotry and occupy our streets without resistance.”

It has been reported figures associated with the neo-Nazi movement have joined the recurring protests, which saw the crowd stage a mock execution of Premier Daniel Andrews using wooden gallows and inflatable beach toy bearing his image on Monday evening.

Key Victorian crossbench MP Andy Meddick’s daughter Kielan was also allegedly attacked on a Fitzroy street on Thursday night and suffered a head injury after being confronted by an unknown man for spray painting over an anti-vax poster.

-with AAP