Australia's most populous states New South Wales and Victoria will impose harsher restrictions on movement if a Covid-19 outbreak is not quickly bought under control, state premiers have said.

Australia has been heralded as a global leader in containing Covid-19, but in the last week it has seen a surge in new cases.

Desperate to contain the outbreak, Victoria state last week forced about five million people into a six-week lockdown. Still, Victoria said it has found another 238 cases in the last 24 hours.