(Updates with three new cases in Victoria)
By Renju Jose
SYDNEY, Dec 30 (Reuters) - Authorities restricted movement and tightened curbs on gatherings in Australia's biggest city on Wednesday, hoping to avoid a coronavirus "super spreader" event during New Year's Eve celebrations after finding a new cluster of infections.
Household gatherings were limited to five people while the maximum number of people allowed to gather in public in Sydney was capped at 30. Residential care facilities were closed to visitors.
"We don't want New Year's Eve to be the cause of a super-spreader," New South Wales state Premier Gladys Berejiklian said as she announced the restrictions would take effect from midnight on Wednesday until further notice.
Berejiklian reported 18 new coronavirus cases on Wednesday, the biggest daily increase in a week, with nine of them part of an outbreak in the city's northern beaches that has grown to more than 100 people over the past week.
NSW Chief Health Officer Kerry Chant said a new cluster in the city's inner west, which includes six members of an extended family living in three different households, is expected to grow as members had joined Christmas gatherings.
The outbreaks in Sydney have dampened plans for the city's New Year's Eve harbour fireworks display, an event televised around the world.
In addition to the new restrictions, authorities have imposed a "green zone" in key vantage spots around the harbour that will be restricted to residents and people with confirmed bookings who get a permit.
The usual 9 p.m. fireworks have been cancelled and the midnight session has been cut to seven minutes.
"If I can stress again, the strongest message to everybody across New South Wales no matter where you are, is please limit your activity and your mobility," Berejiklian said.
In the state of Victoria, after two months of no locally acquired cases, the health department late on Wednesday said three new cases had been diagnosed outside hotel quarantine.
It had no immediate details on how the infections happened.
Australia has reported just over 28,300 COVID-19 cases and 909 deaths since the pandemic began, mostly in Victoria. (Graphic: https://tmsnrt.rs/34pvUyi)