Australia has reintroduced Covid-19 curbs such as mandated mask-wearing indoors, capacity limits and QR code check-ins to cover most of the population as daily infections hit a fresh record, fuelled by the highly infectious Omicron variant.

The changes for 17 million people two days before Christmas mark a reversal of the country's plans for a permanent reopening after nearly two years of stop-start lockdowns as the new variant rages through the community in spite of double-vaccination rates of more than 90 per cent.

Hospitalisations and deaths remained low, but the explosion of infections had created a risk of healthcare workers being furloughed by testing positive, the authorities said, according to Reuters.

The country recorded more than 8,200 new cases, by far its biggest daily rise since the pandemic began, from a previous record of 5,600 a day earlier, mostly in the states of New South Wales (NSW) and Victoria.