Unionists have accused Westpac of underhand tactics after the bank told staff it would send 25 back-office jobs to India.
The Finance Sector Union said workers in the bank's Sydney transaction and unsecured lending operations centre were not consulted about the decision but told after the deal was done and the jobs were gone.
Over 480 of the centre's staff had previously fought moves to offshore their jobs but this time there were no opportunities for consultation, FSU state and capital secretary Geoff Derrick said.
"This cowardly move by Westpac means that no job at the bank is safe," Derrick said.
"For all Westpac employees know, their jobs could be sized up for offshoring right now. And the first they'll know about it is when the bank says we've sold your job to India."
Westpac has signed a contract with Indian outsourcing provider Genpact to remove 25 jobs from the centre and send them to Bangalore.
They involve functions that handle credit card details and special approval loans.
It is believed some have permanent contracts but most are casual employees.
Westpac will find any of the permanent staff a job elsewhere in the bank and will work hard to do the same for temporary employees, a Westpac spokesman said.
The spokesman said the offshoring was less about cutting costs and more about getting access to the latest technology in back-office processing that India can provide.
"You can do things more quickly and that's more effective," the spokesman said.
The union says it is concerned about the risk of cyber fraud beginning to emerge in places like India, where it says data harvesting brokers offer personal information for sale.
Westpac has vowed to keep call centres or other direct customer contact roles in Australia or New Zealand and maintain Australian security standards.
ANZ has sent the most jobs to India in recent years, followed by the National Australia Bank and St George.