Melbourne (AFP)

Melbourne's five million residents will remain confined for at least an additional week, authorities said on Wednesday, failing to stem an outbreak of Covid-19.

The second city of the country entered its sixth confinement on August 5 after the appearance in a school of a source of contamination, linked to the Delta variant, which is much more contagious.

Daniel Andrews, Prime Minister of the State of Victoria, announced that the containment measures will be extended at least until August 19, with new cases having been identified overnight from Tuesday to Wednesday.

"There are too many cases, the origin of which is not known ... for us to be able to end the lockdown now," he said.

In Sydney, more than five million people have entered their seventh week of lockdown which is expected to remain in effect until the end of August.

Since the new outbreak of the epidemic almost two months ago, more than 6,100 cases have been identified in New South Wales.

Hundreds of thousands of people, living in cities outside of Sydney, including Newcastle, Byron Bay and Dubbo, are also in lockdown after the recent emergence of cases.

In a street in Melbourne, whose inhabitants will remain confined for an additional week, August 11, 2021 William WEST AFP

For nearly 18 months, Australia's drastic strategy to fight the virus, via an intense screening and tracing campaign, containments and a virtual closure of its borders, has borne fruit.

But the highly contagious Delta variant appears to have been a game-changer and Australians are tired of these repeated lockdowns.

Authorities now appear to be basing their hopes on a new vaccination campaign, suggesting that some restrictions could be relaxed by vaccinating enough people in the coming weeks.

Just over 20% of Australians have received two doses of the vaccine.

"If we keep the current vaccination rate, we will reach the six million people vaccinated by the end of August, which will allow us to consider granting more freedoms to the population in September and October," said New South Wales Premier Gladys Berejiklian.

The country has so far recorded around 37,000 cases of Covid-19 and 940 deaths linked to this disease in a population of 25 million.

© 2021 AFP