Two deaths, 141 new cases in New South Wales

New South Wales has reported 141 new locally acquired cases of Covid-19 and two deaths, including a woman in her 30s.

At least 62 of the 141 diagnosed people in the 24 hours to 8pm on Saturday were circulating in the community for all or part of their infectious period, Premier Gladys Berejiklian says.

Forty three people are in intensive care in NSW, 18 of whom require ventilation.

Greater Sydney and surrounding regions are in lockdown until at least July 30, while three local government areas in regional NSW are in lockdown until at least 28 July, as health authorities battle to contain a outbreak of the virulent Delta strain.

Ms Berejiklian said the woman in her 30s who died had no pre-existing conditions, demonstrating the severity of the virus.

Eight people have died amid the current Sydney outbreak.

"If anybody thinks this is a disease just affecting older people, please think again ... younger people without pre-existing conditions can also fall victim to this cruel disease," she said.

The 141 cases came from a record of more than 102,000 tests.

It comes as the NSW treasurer calls for the reintroduction of the JobKeeper wage subsidy scheme amid Greater Sydney's Covid-19 outbreak and Labor demands a summit to discuss the health crisis.

But the federal government has poured cold water on Dominic Perrottet's suggestion, arguing its current support payment structure is simpler and more flexible.

Disquiet over the lockdown erupted dramatically on Saturday afternoon, as thousands marched through Sydney's CBD.

At least 57 people have been arrested over the protest action, which Ms Berejiklian said left her "disgusted".

Two men have also been charged with allegedly striking a police horse.

A team of more than 20 detectives is working to identify more of the protesters and either charge or fine them.

The latest lockdown escalation has prevented all but the most essential workers in Cumberland and Blacktown local government areas leaving those areas, joining Fairfield residents.

Ms Berejiklian has described vaccination as the way out of the outbreak, but her plea for more Pfizer stocks has been rebuffed.

Instead, NSW will have to settle for 50,000 more Pfizer doses from the federal government's national stockpile.

Three regional NSW local government areas in the state's central west are also under stay-at-home orders until at least July 28.

Local elections across NSW have also been postponed by three months to December 4.