Hundreds of fines have been issued and dozens charged in Sydney after anti-lockdown protesters marched and clashed with police in what one deputy commissioner called “violent, filthy, risky behaviour”.

The Australian prime minister, Scott Morrison, said on Sunday the previous day’s protests – in which thousands breached the region’s coronavirus measures to protest – were “selfish and self-defeating”, adding: “It achieves no purpose. It won’t end the lockdown sooner.”

The New South Wales premier, Gladys Berejiklian, said she was “utterly disgusted” by the scenes, saying: “It just broke my heart that people had such a disregard for their fellow citizens.”

Detectives are now combing social media and footage from CCTV and police-worn body cameras to identify and punish everyone who defied stay-at-home orders, which are now entering their fifth week.