Australia's Melbourne continues lockdown for a second week

Australia's second-biggest city Melbourne will stay locked down for a second week after reporting 20 new coronavirus infections as it struggles to stamp out infections caused by the highly infectious Delta variant of the pandemic, Reuters reports.

Melbourne had been due to exit the lockdown on Thursday, the sixth for its five million people in stop-start battles against the coronavirus also seen elsewhere across the country have triggered frustration and discord.

But Victoria state Premier Dan Andrews confirmed strict stay-at-home orders will remain in place until at least August 19 after authorities were unable to trace how several of the 20 people confirmed as new infections on Wednesday became infected.

"If we were to open, then we would see cases akin to what is happening, tragically, in Sydney right now," Andrews told reporters in Melbourne, referring to an outbreak in Australia's most populous city that has spread to thousands despite Sydney being in week seven of its own lockdown.

"We have seen a surge in the number of cases and (that is) expected to continue," New South Wales state Premier Gladys Berejiklian told reporters in Sydney, reporting another 344 new infections in the past 24 hours, close to the city's single-day record.

Berejiklian said the Sydney lockdown, which has grown to include several areas north of the city, will also be expanded to include Dubbo, a small city about 400 kilometres (248 miles) northwest of Sydney. Sydney is scheduled to remain in lockdown until the end of August.

Most expect the restrictions to be extended, despite a recent surge in people seeking vaccinations. Australia has so far fared much better than many other countries in the developed world during the pandemic, with just under 37,000 infections.

The deaths from the disease increased to 944 on Wednesday after two people, including a man in his 30s, died in Sydney.