Updated
Customers are being directed to post offices as another two Sutherland Shire bank branches close.
The National Australia Bank at Cronulla will close on September 15, while the closure of the Westpac branch in Engadine has also been confirmed, with customers yet to be notified of an exact date.
Other branch casualties in recent weeks include Westpac Cronulla and the Commonwealth Bank at Sutherland.
The Finance Sector Unit says the situation has reached "crisis point", with 37 branches to be shut by the Big Four banks Australia-wide over the next few months.
The union is seeking government intervention "to protect local economies and save what's left of Australia's bank branch network".
An NAB spokesman said of the Cronulla branch closure, "As more and more customers are choosing to bank online, we've made the difficult decision to close the Cronulla branch on 15 September.
"Increasingly Australians are banking digitally, with more than 94 per cent of customer interactions now taking place over the phone, by video or online. While the Cronulla branch will no longer be there, we will still be there for our customers - just in different ways.
"Over the past few years, fewer customers are coming into branches to do their banking and foot traffic has lessened, which has been accelerated by COVID. More than 60 per cent of our Cronulla customers have only visited the branch once in the last year and many are also preferring to use other branches in the area.
"We commenced notifying our customers in July and have been providing information about the various banking alternatives available. These conversations will continue at the branch over the coming weeks. Alternative ways to bank include our partnership with Australia Post and the Bank@post service as well as connecting with our mobile bankers, home lending specialists or business bankers in person or for phone or video appointments. Bank@post is available at Australia Post outlets, including the Cronulla Post Shop.
"Importantly, there will be no job losses. We work closely with our colleagues on opportunities for them to continue to support customers either through other branches or across phone and digital channels."
A Westpac Group spokesman said of the Engadine branch closure, "With more than five million digitally active customers, we're investing in services to complement how our customers choose to bank.
'Declining customer use of branches means that in some instances, we may take a difficult decision to leave a branch location. In these instances, we continue to support our customers by expanding access via Bank@Post, telephone, mobile and virtual banking.
"We take steps to ensure customers are notified in advance about the changes and are directly connected with the services they need to continue to do their banking. For those who are new to digital banking, or may require more assistance with the changes, we provide dedicated support and education to make the transition easier.
"Our customers have access to Westpac Miranda located 9.8km away as their supporting branch. Many customers can continue to access the same cash services locally via Australia Post at Engadine Post Shop, just 140m away from our current branch. We also have a St.George ATM located at Engadine Woolworths and customers can call us on 132 032 to talk to one of our bankers.
"As we continue to adapt to our changing customer needs, this will result in new opportunities within the Westpac Group as we grow our phone, digital and virtual offerings. We have a robust process in place to assist employees to find new opportunities within Westpac Group, meaning the majority of employees affected secure a new role and continue their career in the Group."
Finance Sector Union national secretary Julia Angrisano said the Big Four had closed more than 550 bank branches across Australia since January 2020.
"We must act to stop the banks walking away from communities in our suburbs and towns. It's time to examine the impact of these closures which have hit hundreds of communities across the country," she said.
Ms Angrisano said for decades the major banks had been supported by government as part of the "four pillars policy" but had failed to support local communities in return.
"Instead the banks continue to shut down branches, sack workers and turn their backs on customers and businesses. Cost savings from branch closures are designed to increase the banks' already huge profits," she said.
"The Big Four are said to be 'too big to fail' and have enjoyed Government guarantees in the past but they are not too big to regulate when it comes to the branch network."
Ms Angrisano said the latest closures included 24 by the Westpac Group, five by the CBA and eight by the NAB, with the loss of 182 jobs.
"Communities depend on the banks to deliver financial services but if we don't stop the current trend, there will be no branches left," she said.
Ms Angrisano said self-regulation had not worked. She said the Australian Banking Association's commitment to consulting the community about proposed branch closures, was being ignored.
"We need an inquiry into bank branch closures to assess the impact on local communities when the banks pull out of suburbs and towns."
"The UK has a formal 'community impact assessment test' and we need a similar test to ring-fence our branches and make sure banking services the public which they derive their profits from."
Ms Angrisano said she would seek the assistance of the Albanese Government to ensure continuing delivery of banking services to the Australian community, especially in regional areas.
"The Morrison Government did nothing to protect the public interest and maintain bank branches. They neglected this issue and now more regional communities are facing a future without a bank."