New South Wales has recorded 210 new locally acquired Covid-19 cases in the 24 hours to 8.00pm yesterday.
Health authorities have also recorded another death linked to the virus, a man in his 60s in south-west Sydney. He died at home.
He is the state's 70th Covid-19 fatality and the 14 of this Delta outbreak which began on 16 June.
Of today's new cases, 21 were infectious while in the community, 11 were in isolation for part of their infectious period and the isolation status of 120 remains under investigation.
Only 88 of the 210 new cases were linked to a known case or cluster.
NSW Health Minister Brad Hazzard said a majority of today's new cases continue to come from Sydney's south-west and west and that small businesses and shops tend to be the epicentre of the new outbreaks.
Two thirds of the new cases in NSW are in people aged under 40.
"It definitely is circulating in the younger community and I want to stress that another 210 locally acquired cases, two-thirds, two-thirds, 138 cases, were people under the age of 40 years old," Hazzard said.
South-east Queensland has been put into a snap lockdown from 4pm today local time after six new locally acquired cases of the Delta Covid-19 variant were reported.
All are linked to a 17-year-old high school student from Brisbane's inner-west who tested positive on Thursday.
Chief Health Officer Dr Jeannette Young said whole genome sequencing had linked the cluster stemming from the school student to two people who had returned from overseas and were in hotel quarantine.
Dr Young said the lockdown had to be particularly restrictive due to the highly infectious nature of the Delta strain and it was more important than ever for people to come forward for testing at the first sign of symptoms.
The lockdown will mean people can only leave their homes to obtain essential goods, essential work school or childcare, to exercise but only with one person from outside the household or to care for a vulnerable person or seek medical treatment or a Covid-19 test or vaccination.
Victoria has recorded two new local Covid-19 cases which have both been linked to known outbreaks.