Australia's state of New South Wales has reported another record day of Covid-19 cases as authorities in the country's second largest city of Melbourne rush to trace the source of its outbreaks, reports AFP.

Australia's three largest cities are in lockdown as New South Wales records 319 community cases of the virus and five more deaths — a third straight day of record case numbers.

With the virus continuing to spread through Sydney's sprawling suburbs, despite the city heading into its seventh week of lockdown, state Health Minister Brad Hazzard has expressed frustration that people appear to be ignoring restrictions and urge residents to stay at home.

“That is the biggest thing you can do for all of us and for yourself, to make sure that we beat this Delta virus that is wreaking havoc across the world,” Hazzard told media.