Plans to let thousands of frontline workers ring in the new year around Sydney Harbour were ditched on Monday as authorities work to suppress a growing cluster of virus cases in Australia's most populous city.

Ordinarily, hundreds of thousands of eager partiers would flock to vantage points for the midnight fireworks launched from the Sydney Harbour Bridge on the New Year's Eve.

Although allowing the usual hordes of revelers had been ruled out in 2020, officials had planned to welcome around 5,000 workers to the foreshore as a token of thanks for their work against the pandemic. 

But that idea has now been axed over fears the celebrations could turn into a super-­spreader event.

"We've abandoned our plans in terms of any foreshore viewing of the fireworks from the Sydney CBD, so that won't be allowed," said Gladys Berejiklian, state leader of New South Wales, of which Sydney is the capital.

Permits will also be required to enter some parts of the city as celebrations will be limited to controlled, socially-distanced events and small gatherings at people's homes.

"We do recommend very strongly that people watch the fireworks on TV or go to a local venue outdoors which is not on the foreshore and doesn't have that cramped crowding," Berejiklian said.

The decision to tighten ­restrictions comes as a cluster of cases on the city's ­northern beaches grew to 126 and a ­lockdown for several suburbs was extended until January 9.