Adelaide, Dec 6 (IANS): Authorities in South Australia (SA) on Monday warned the state's border could still remain shut to interstate travellers in response to the Omicron Covid-19 variant.

SA Police Commissioner Grant Stevens said on Monday he could not rule out hard border closures to keep the Omicron variant out of the state before Christmas, reports Xinhua news agency.

His comments came two days after the SA government on Saturday imposed new restrictions on travellers from the Covid-hit Australian Capital Territory (ACT), New South Wales (NSW) and Victoria requiring them to be tested on arrival.

"We've been watching the emergence of the Omicron variant. There was a recommendation from SA Health that we shut our borders to New South Wales, Victoria and the ACT on the basis that we simply didn't know enough about this variant," Stevens told Adelaide's FiveAA radio.

"We are watching very closely, we can't rule out border closures, but if we do that, it will be on the basis of legitimate concerns that need to be responded to."

The number of confirmed Omicron infections in Australia on Monday increased to 28 after NSW reported 10 new cases, sparking concerns of community transmission.

On Monday, Australia reported more than 1,200 new Covid-19 cases and six deaths as the country continues to battle the third wave of the pandemic.

So far, about 93 per cent of Australians aged 16 and over have received one vaccine dose and 88 per cent have had their second dose, according to the Department of Health.