Commonwealth Bank is under pressure to disclose the extent of its planned job cuts across its branches and technology division, alleged to affect 10,000 employees.
The Financial Sector Union said it wrote to CBA chief executive Matt Comyn asking to confirm or deny these reports so that "workers know where they stand."
"CBA needs to come clean and tell workers what their plans are. Unconfirmed speculation of this size can only lead to uncertainty and has far-reaching negative impacts on employees," the FSU said.
The FSU referred to an article in The Australian, which alleges Comyn has a "secret plan" to cut more than 10,000 employees.
The FSU said it understands Comyn's plan includes shutting down 300 branches.
FSU national secretary Julia Angrisano commented CBA is a highly profitable company which relies on its staff to deliver financial services to its large customer base and Comyn is "on the wrong track if he thinks shutting down branches and sacking staff will enhance the bank's reputation in the community and increase profits."
Angrisano said if the report is incorrect, Comyn must immediately notify the bank's 50,000 staff that their jobs are not on the line.
If the reports were correct, comments from CBA that it was working to improve 'outcomes for customers' and to run the bank 'efficiently and effectively to invest in the future' were "farcical," she added.
CBA responded to the FSU, saying "these reports as misleading and unnecessarily alarming."
"CBA is committed to our people and are disappointed that speculation may be repeated as fact," it added.
In its half-year results released in February, CBA flagged there was need to manage costs where it makes sense for efficiency and as part of good business discipline.
"This is an ongoing focus for our business to enable us to invest in things that will make a measurable and long-term difference in the lives of our customers," CBA said.
The suggestion that 300 branches are under consideration is also "incorrect and misleading."
"We remain committed to our decision to limit our review of branches in regional and rural towns during this financial year, given the conditions currently experienced by rural NSW and Queensland."
Financial Standard understands the banking giant was restructuring its digital infrastructure, leading to a number of redundancies in technology and back-office jobs.
In early March, Financial Standard reached out to CBA to confirm the speculation.
CBA did not disclose how many in its workforce was affected. A spokesperson said in a statement: "We have recently revised the operating model of our technology division so that it better aligns with the group's strategy. The newly announced changes have not impacted teams or the systems that our technology teams use at this time."
Furthermore: "We regularly review our business and operations to ensure we can deliver our strategy to become a simpler, better bank."
Financial Standard also understands changes are taking place in CBA's SMSF business.
CBA said in a statement that its subsidiary CommSec "is making some changes to help us better serve our customers' needs."
"As part of this, the structure of some teams has changed. CommSec is not pulling out of the SMSF market and our customers will continue to receive the same level of support and industry-leading content."
The big four banks and AMP have exited SMSF lending, leaving Macquarie, Bendigo Bank and Bank of Queensland in the market.