Update - 2pm
All of Greater Sydney, the Blue Mountains, Central Coast and Wollongong will go into lockdown from 6pm today.
NSW Premier Gladys Berejiklian announced the snap lockdown at a press conference at 2pm today - just hours after she warned Sydneysiders that more restrictions could be imminent as early as today.
It came after 12 additional COVID-19 cases were detected to 8pm last night.
Ms Berejiklian made the announcement shortly after a crisis Cabinet meeting and taking the advice of NSW Health and the Chief Health Officer Dr Kerry Chant.
The two-week lockdown will be in force until midnight on Friday, July 9, unless there is a "dramatic change" to case numbers.
Anyone from those areas placed into lockdown who have already left to go on holidays must follow the same rules as if they were at home, Dr Chant said.
Dr Chant said this meant they could not attend a restaurant in the area they are visiting.
She said this applied to anyone who resides in the lockdown areas for 14 days from when they were in a hot spot, and dates back to June 21.
Minister for Health Brad Hazzard said a public health order would be drafted today to ensure anyone who is able to work from home can do so.
There will be four reasons people can leave home: shopping for food or other essential goods and services; medical care or compassionate needs; to exercise outdoors in groups of no more than 10 people, and essential work or education if you cannot do so from home.
MORE TO COME.
Earlier - 11am
NSW Premier Gladys Berejiklian has warned Sydneysiders that more restrictions could be imminent as early as today after 12 additional COVID-19 cases were detected to 8pm last night.
The total number of new cases reported to 8pm last night was 29, of which 17 had already been reported. All but three are linked to the Bondi cluster.
Buf of most concern to the government and NSW Health is the fact the many of the new cases were outside the local government areas of concern. Also worrying is a workplace outbreak in Marrickville, which could have been spread throughout Sydney by infectious delivery drivers.
Ms Berejiklian addressed a press conference at 11am and said a crisis Cabinet meeting would be held today and she would act on the health advice she received regarding further restrictions as early as today.
"The health advice is evolving and there will be more advice during the day," she said.
"If we need to take further action we will notify the community."
She implored anyone in the local government areas of concern not to leave metropolitan Sydney.
"We do not want to spread it," she said.
"This particular variant is contagious and transmissible like we have never seen."
NSW Chief Health Officer Dr Kerry Chant said of most concern was that 12 of the 29 cases reported to 8pm last night were not in isolation when they were infectious.
A long list of exposure sites would be expected in coming days.
Minister for Health Brad Hazzard described the current Delta variant as a "formidable foe" which was managing to stay one step ahead of NSW Health.
"No matter what steps we take, the virus counter-attacks," he said. "That is giving us a high level of concern."
NSW Health said there had now been 82 locally acquired cases since June 16. Of those 80 are linked to the Bondi cluster and 20 of those are associated with the West Hoxton Park birthday party.
NSW Health said its ongoing sewage surveillance program had detected fragments of the virus that causes COVID-19 at a total of 12 sewage treatment plants, including Cronulla and Caringbah.
"Everyone residing or working in and around these areas is asked to be especially vigilant for any symptoms that could signal COVID. If they appear, please get tested and self-isolate immediately," NSW Health said.
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