NSW Health has issued alerts for major shopping outlets and public transport routes in the heart of Sydney, amid concerns the city's Covid-19 outbreak will spread further.
The move comes as people were fined for attending a wedding against lockdown rules, and New Year's Eve celebrations are restricted.
Among the affected venues are the David Jones store on Castlereagh St, the Uniqlo in MidCity and Kinokuniya bookstore on George St.
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There are also alerts for the eastern suburbs, including Bondi Beach Woolworths and Edgecliff Coles.
Meanwhile, police have issued fines to nine northern beaches residents after they were caught attending a wedding in Sydney's CBD.
Another three guests are expected to be fined A$1000 each for violating Covid-19 rules by attending the reception, which is understood to have been held at Doltone House in Pyrmont on Sunday.
It comes as strict new restrictions for Sydney's New Year's Eve celebrations are announced.
There will be no crowds to festivities around Sydney Harbour this year, despite previous restrictions allowing frontline workers access to view the midnight fireworks via a permit system.
The tradition of camping out at vantage points around the city has also been banned, unless it's a council-run ticketed event.
"As you know, previously we'd allocated spots along the foreshore for front-line workers from across the state to be able to come and enjoy the fireworks," Premier Gladys Berejiklian said on Monday.
"Unfortunately we're going have to cancel that. We think it's too much of a health risk having people from the regions and from Sydney and from broader regional areas congregate all in the CBD and the advice to date has to all of us to try to avoid the CBD on New Year's Eve."
New South Wales recorded five new locally-acquired cases of Covid in the 24 hours to 8pm. Four are linked to the Avalon cluster.
On Sunday, the state recorded seven new cases. The northern beaches cluster is now at 126.
Wedding guests fined
NSW Police have fined nine northern beaches residents who attended a wedding in Sydney yesterday in violation of Covid-19 restrictions.
Officers were called to the wedding reception in Pyrmont, in the Sydney CBD, about 5pm and found more than a dozen guests were residents of the northern beaches region, which is under strict stay-at-home rules.
The wedding venue is understood to be Doltone House on the Sydney Harbour foreshore.
Nine people were issued with A$1000 penalty infringement notices, including a man and woman, both aged 43, from Allambie Heights; a Narraweena woman, 33; a Frenchs Forest man, 27; three women, aged 19, 22 and 28, from Beacon Hill; and two men, aged 23 and 63, also from Beacon Hill.
Police expect to issue penalty infringement notices to three other people: a man, 34, and woman, 36, from Frenchs Forest, and a Beacon Hill man, 26.
Police investigations are continuing. Doltone House has been contacted for comment.