Anti-lockdown protesters have marched in major Australian cities, as Covid cases spiked to record numbers in Sydney and authorities warned of a “continuing and growing problem”.

Thousands of angry, unmasked people marched through the Sydney central business district on Saturday afternoon demanding an end to the city’s lockdown, which is entering its fifth week.

After protesters were dispersed, the New South Wales police minister, David Elliott, announced the formation of a strike force to identify each of the 3,500 protesters at the “super spreader” event.

Elliott said 57 people were arrested and several police officers had been assaulted.