A Christian leader in Australia says "unthinkable" costs are being incurred by "foolish" 'Covid-zero' policies.

Martyn Iles, head of the Australian Christian Lobby (ACL), questioned why the policy was being pursued by state premiers at a time when more and more people are being vaccinated, and the Covid death rate remains low.

"This isn't a sustainable solution," he said.

"Multiple premiers are threatening the same approach, even after we reach the 70-80% vaccine threshold.

"But the virus is not going anywhere. We cannot do this forever. Indeed, the longer we delay the inevitable, the greater the cost will be.

"We are incurring unthinkable additional costs for fear of what we must face... lives, livelihoods, children, the economy and democracy are all straining under the burden of 'Covid-zero'."

Anti-lockdown protests have been held across Australia in the past week, with some turning violent and dozens of arrests being made.

Australian Prime Minister Scott Morrison has said the country cannot "stay in the cave forever".

He is urging states to lift restrictions once national vaccination rates have reached 70% to 80% of the adult population.

"The national plan is our deal with all Australians. It is the understanding that we have with Australians making their sacrifices now, and who have made them over such a long time, that that sacrifice will get them to the next step, because if not at 70% and 80% then when?" Morrison said on Monday.

"We must make that move and we must prepare to make that move and we must prepare the country to make that move. The lockdowns now being endured are taking an extremely heavy toll. Both on the mental and physical health of Australians and on the economic success of Australia."

Australia has been criticised for its slow rollout of the vaccine, with only around a quarter of the population has vaccinated so far, trailing far behind other Western countries, including the UK at 62%, and the US, where 52% have received both doses.

Mark McGowan, premier of the state of Western Australia, says he wants to "crush and kill" the virus.

The Queensland government has indicated in recent days that it will not ease state border restrictions even once the vaccination rate has reached 80% because of concerns over the Delta outbreak in neighbouring New South Wales.

Australian researchers warned this week that ending restrictions once 80% of the population has been vaccinated could lead to 25,000 deaths and 270,000 cases of long Covid. 

Morrison has dismissed the figures as "not realistic" because he says vaccination levels will continue to increase and some public health measures will remain in place even after lockdowns and other restrictions are ended.

ACL's Iles suggested Australians need to learn to live with Covid-19.

"Fear is making us foolish," he said.

"3,345 suicidal people called LifeLine on a single day this week – yet another record. Our children simply won't be able to pay back the debt levels. Many small businesses are finished. We are not living (or even leaving the house) for fear of dying. We are giving up total authoritarian power to people who despise what we believe. Compassion is dead, with callous disregard for those torn apart or mourning.

"And our premiers are telling us all this and more will continue - despite decent levels of vaccination.

"It seems we're too afraid to accept the brutal reality that, with half-decent levels of vaccination, a tiny proportion of Delta cases will die. We'll spend anything to delay it."

He added, "Fearfulness and fearmongering are winning the day. This will change only when public opinion changes, and when premiers stop getting the approval ratings they crave.

"And Christians - that's you and me - should lead the way."