SYDNEY, July 28 (Reuters) - Australia's New South Wales state authorities on Wednesday (Jul 28) extended a COVID-19 lockdown in state capital Sydney for another month after weeks-long curbs failed to contain an outbreak of the highly infectious Delta virus variant.

Lockdown rules were due to end on Friday but restrictions will now run until Aug 28, state Premier Gladys Berejiklian told reporters in Sydney.

A total of 177 new locally acquired cases were detected in New South Wales, up from 172 a day earlier.

The office of the premier of New South Wales did not immediately respond to a request seeking comment.

Of particular concern is the growing number of people positive with the Delta strain moving around in the community. Unless that number returns to near zero, tough restrictions would continue, authorities have said.

Around one in three new cases detected over the last several days have spent time in the community while infectious.

As Sydney braces for tougher restrictions for most of August, Victoria and South Australia states came out of lockdown restrictions on Wednesday after getting on top of virus outbreaks.

Australia has kept its COVID-19 numbers relatively low, with just over 33,200 cases and 920 deaths since the pandemic began, but the fast-moving Delta strain and low vaccination coverage have frustrated residents.

Many Sydney businesses have been forced to shut, with the lockdown expected to take a heavy toll on Australia's A$2 trillion (US$1.50 trillion) economy.

Finance Minister Simon Birmingham said the federal government could provide more support to employers depending on the decisions made by New South Wales authorities.

"The (prime minister) will have more to say on that later today," Birmingham told the Australian Broadcasting Corp on Wednesday.