New local COVID-19 infections in NSW has spiked to a record high of 239 as authorities tighten restrictions on masks and movement for two million people in Sydney.
Two more people have also died - a woman in her 90s and a man in his 80s, both from southwest Sydney - taking the death toll for the outbreak to 13.
Premier Gladys Berejiklian acknowledged the number of local cases would get worse in the coming days, given the high number of people infectious while in the community.
At least 22 of those people were circulating in the community for part of their illness, and 66 were infectious in the community for the entire time.
The isolation status of 70 cases remains under investigation.
"We can only assume that things are likely to get worse before they get better," the premier said on Thursday.
But she rejected suggestions her government had failed by imposing restrictions too late and too gradually, saying there was "no perfect way" to respond to an outbreak of the highly contagious Delta strain.
"We have harsher restrictions in place than any other state has ever had," she said.
"If you look at other places around the world and the way the Delta strain has taken over communities, even where vaccination rates have been higher ... we can take comfort in the fact we haven't had thousands of cases."
Thursday's count exceeded the previous pandemic high of 212, set in March 2020 when most cases came from overseas and no hotel quarantine system was in place.
Two million people in eight western Sydney local government areas cannot leave the area unless they are essential workers.
Ms Berejiklian tightened restrictions further on Thursday, saying she had accepted police advice to subject the virus-hit LGAs to harsher compliance measures.
Masks will be mandatory at all times - including outdoors - and people will be restricted to within five kilometres of their home.
Police will also be able to shut down businesses that repeatedly breach public health orders.
Police Commissioner Mick Fuller says "nothing is off the table" in terms of stronger compliance, saying officers will be going door to door looking for people in the wrong house.
On Thursday afternoon he formally requested the assistance of 300 defence force personnel for that operation.
On Thursday evening Defence Minister Peter Dutton said in a statement that the requested personnel would deploy from Friday to train over the weekend and on Monday commence working under the direction of NSW Police.
The military has supported hotel quarantine policing, logistics in the Police Operations Centre and compliance during a 2020 border operation.
Federal Health Minister Greg Hunt said extra support for NSW will be the focus of an emergency meeting of the Australian Health Protection Principal Committee on Thursday night.
New cases reported Thursday came from almost 111,000 COVID-19 tests - a daily record.
There are 54 COVID-19 patients in intensive care, including 10 aged under 30. 22 are on ventilators.
Chief Health Officer Kerry Chant said more than half of people with the virus were under 50 while a quarter of NSW residents aged over 70 remained unvaccinated.
She implored those people to seek vaccination immediately, with supplies of AstraZeneca abundant.
Nearly a third of NSW's 8.17 million residents have received one dose, with 80,000 jabs administered on Wednesday.
Other lockdown measures announced on Wednesday include more financial support for businesses and workers, a "singles bubble" and a partial reopening of the construction sector.
Year 12 students will also be able to return to school on August 16, aided by rapid antigen testing.
Up to 40,000 Pfizer doses will be redirected to vaccinate students in virus-hit areas but students won't be forced to get the shot.
The Commonwealth Bank said in an economic briefing on Wednesday that it expected the Delta outbreaks in Sydney, Melbourne and Adelaide to cause a 2.7 per cent national economic contraction in the September quarter.
This could cost up to 300,000 NSW jobs.
Australian Associated Press