NSW has recorded a worrying rise in Covid-19 cases, with officials confirming 10 new community infections since yesterday.
Premier Gladys Berejiklian has confirmed one of today's Covid-19 cases is not linked to the current cluster in Sydney's eastern suburbs. This case is a student at a primary school in Waverly.
The NSW Government will extend its current mask restrictions for one more week and the rule will now cover the whole of Sydney.
At a media briefing today, Berejiklian said more cases in the coming days are expected. There are now 21 infections in Sydney's Covid-19 outbreak.
NSW Transport Minister Andrew Constance issued a warning to NSW residents this morning, saying they were "clearly in a danger period" of the outbreak.
"I think when you hear the health minister say there is a clear and present danger, he hasn't done that lightly," he told ABC's News Breakfast.
He noted that some Sydney residents seemed to be ignoring the current restrictions around masks.
"Everybody has to play their role as they have over the last year and a half, we have to ringfence the current seeding and make sure we come out of this as quickly as we can," Constance said.
The danger posed by the highly infectious Delta strain of Covid-19 has been made abundantly clear to authorities, with CCTV footage inside Bondi Junction Westfield demonstrating how quickly the strain can spread.
NSW's chief health officer Dr Kerry Chant said the footage showed the virus transmitting between two people during a "momentary crossover" in the shopping centre.
"We know that there's been three people that have been exposed on both June 12 and June 13," she said yesterday.
"In one, we actually have CCTV footage of the encounter and it is basically a crossover of individuals. They are clearly facing each other but it is literally someone moving across from each other for a moment, close, but momentary.
"In two other cases, we haven't been able to, with CCTV footage, look at the exact same crossover point, but we know they were 20 metres [apart], signing in at different venues at the same time or in that area so we suspect they did cross over."
Berejiklian described the encounter as "scarily fleeting", saying the pair didn't even physically touch each other, with the virus instead being transferred as they came into "the same airspace".
"That's how contagious it is," she said.
The Delta strain, which is believed to be up to 50 per cent more infectious than other variants, first emerged in India and has since spread to dozens of other countries.
It was discovered in the Australian community for the first time earlier this month in Melbourne, when the city was dealing with its own Covid-19 outbreak.
Genomic sequencing has shown the variant on the loose in Sydney matched "perfectly" with a sequence from the US.
Expert calls for snap lockdown
Today's numbers follow calls from a top epidemiologist for a snap three-day lockdown in Sydney.
Epidemiologist and World Health Organisation adviser, Professor Mary-Louise McLaws, told ABC radio on Sunday that NSW needs to take this outbreak of the Delta variant "very seriously".
"If the numbers go up any further we should really be thinking about a three-day lockdown," she said.
McLaws also said masks should be made mandatory in all public areas in Greater Sydney.
Berejiklian has previously refused to rule out bringing in tougher restrictions in order to control the outbreak.