Australian Prime Minister Scott Morrison speaks during a press conference at Parliament House in Canberra, Wednesday, Dec. 22, 2021. Morrison explicitly rules out a "heavy-handed" approach, including reintroducing indoor mask mandates as new COVID-19 cases surge. Credit: Lukas Coch/AAP Image via AP

Australia on Thursday reported a major spike in coronavirus infections, prompting the worst-hit state of New South Wales to reimpose mask wearing indoors, a day after Prime Minister Scott Morrison rejected lockdowns or mask mandates for the entire country to slow the spread of the omicron variant.

New South Wales recorded 5,715 new cases, up from 3,763 and almost as many as were recorded across all of Australia on Wednesday. New South Wales also reported one death.

There were 347 people in New South Wales hospitals, up from 302 the previous day, and 45 in intensive care units, up from 40. Victoria state also saw a sharp increase, reporting 2,005 new infections on Thursday and 10 deaths.

Morrison on Wednesday convened a Cabinet meeting with leaders of Australia's states and territories. He later told reporters lockdowns and federally ordered mask mandates are not being considered.

A decision on whether the gap between second vaccine doses and booster shots will be shortened will be left to the Australian Technical Advise Group on Immunization.

"My message is stay calm, get your booster, follow the commonsense behavioral measures as you're going into Christmas and we look forward to that," Morrison said. "Australians have worked very hard to have this Chrismas together and we want to protect that."

But in the face of fast-rising cases, New South Wales Premier Dominic Perrottet bowed to pressure from and others to announce that from midnight Thursday masks must be worn in indoor settings. Perrottet also announced the reinstatement of density limits that will allow only one person per 2 square meters indoors.

"We've always said as we have moved through this that we will monitor the situation and the evidence in front of us," Perrottet said. "The key indicators to us are not the case numbers but rather ICU numbers, hospitalizations and in addition to that, importantly, the ability of our health care workers here in our state to provide the care that people need if they're seriously ill as they come into the hospital system."

Perrottet described the new requirements, which will be in place until Jan. 27, as "modest" and cautious.

Victoria state moved early Thursday to expand current regulations to require residents aged over 8 years to wear masks in hospitality, entertainment and office settings. The new rules also will come into force at midnight Thursday.

"This is a sensible response which will allow businesses to stay open, bars and restaurants to continue to stay open and major events to go ahead," Victoria Acting Premier James Merlino said. "Masks are a cheap and effective way to maintain the health of the community. It's something have been calling for."

Australia's federal Health Minister Greg Hunt said mask wearing and other regulations are a matter for states and territories to decide individually.

"But states and territories with their public health orders, whether it's QR codes in New South Wales, whether it's the in Victoria, have responded well and I think it's important for me to acknowledge that," he said.