Australian authorities on Friday pleaded with Sydney’s five million residents to stay home, warning a three-week lockdown may be extended as they struggle to control a COVID-19 outbreak, with the city reporting the biggest rise in local cases in 2021.Hundreds of extra police patrolled parts of Sydney to enforce the city’s lockdown orders imposed to stamp out an outbreak of the highly infectious Delta variant which now has a total of more than 400 cases.“New South Wales (state) is facing the biggest challenge we have faced since the pandemic started,” state Premier Gladys Berejiklian told reporters in Sydney. “At the moment the numbers are not heading in the right direction.”“Please do not leave your house.