About 50,000 people have been urged to evacuate their homes as floods hit Australia's largest city for the third time this year.

Parts of Sydney have received about eight months of rain in four days.

Roads have been cut off, some houses are under water and thousands have been left without power.

Widespread flooding across Australia - driven by a La Niña weather pattern - has killed more than 20 people this year, many in New South Wales (NSW).

More than 100 evacuation orders have been issued across Greater Sydney for the current emergency.

Australia has deployed hundreds of soldiers to Sydney to help enforce a Covid lockdown. A Delta outbreak which began in June has produced nearly 3,000 infections and led to nine deaths.

Australian Defence Force soldiers will undergo training on the weekend before beginning unarmed patrols on Monday. But many have questioned whether the military intervention is necessary, calling it heavy-handed.

The lockdown - in place until at least 28 August - bars people from leaving their home except for essential exercise, shopping, caregiving and other reasons. Despite five weeks of lockdown, infections in the nation's largest city continue to spread. Officials recorded 170 new cases on Friday.

Soldiers will join police in virus hotspots to ensure people are following the rules, which include a 10km (6.2 miles) travel limit. State Police Minister David Elliott said it would help because a small minority of Sydneysiders thought "the rules didn't apply to them".

Information provided by health officials indicates the virus is mainly spreading through permitted movement.