SYDNEY: Australian Prime Minister Scott Morrison said on Monday the country must begin to ease strict COVID-19 restrictions once vaccination rates increase, with over half of all Australians enduring weeks-long lockdowns to curb Delta outbreaks.

Some states have flagged they may not stick to a national plan that would include relaxing border controls, worried about a surge in cases in the country's southeast, with Sydney breaking new one-day records for infections.

"(Lockdowns) cannot go on forever. This is not a sustainable way to live in this country," Morrison said during a televised media conference in Canberra.

"Because if not at 70% and 80%, then when? Then when? We must make that move and we must prepare to make that move and we must prepare the country to make that move."

The federal government last month unveiled a four-stage plan to relax restrictions once 70% of its 25 million people aged over 16 are vaccinated, with stringent lockdowns "unlikely" to be required.

When vaccination coverage reaches 80% only "highly targeted lockdowns" would be necessary and vaccinated Australians would be free to travel interstate.

However, Western Australia and Queensland states have raised concerns that the plan was agreed before a large outbreak in New South Wales (NSW), where daily cases have topped 800 for the last three days.

On Monday, NSW reported 818 cases, most of them in Sydney, slightly down from the record 830 a day earlier.

Australia managed the pandemic better than many other developed countries but a slow vaccine rollout has thrown Sydney and Melbourne, its largest cities, and capital Canberra into lockdowns to combat outbreaks of the Delta variant.

Nationally, 30% of people above 16 are fully vaccinated, while 52% have had a least one dose. Vaccinations are running at a record pace but the target of 80% fully vaccinated will not be reached until December at the current rate.

NSW Premier Gladys Berejiklian said on Monday the state's residents must learn to live with the virus, urging people to get vaccinated soon.

"Once you get to 80% double dose, every state will have to live with COVID. You cannot keep Delta out forever," she said.

Australia has reported just over 44,600 cases in total. There have been 984 deaths, although the death rate has declined since last year.