More than one million people in Sydney's central and eastern suburbs, including Bondi Beach, will be locked down after a jump in Covid cases.

The Australian city is battling to contain an outbreak of the highly infectious Delta variant.

Officials reported 17 new cases on Friday, taking the cluster to 65 cases.

It is the first lockdown in Australia's largest city since December. The country has consistently maintained very low rates of Covid transmission.

The stay-at-home order will affect the city centre and inner-city suburbs, as well as beachside suburbs in the east.

"We don't want to see this situation linger for weeks. We would like to see this situation end sooner rather than later," New South Wales Premier Gladys Berejiklian said.

But she added that medical experts believed only a targeted lockdown was necessary for now, sparing the wider city from shutting down.