Westpac Bank says it can't comment on alleged links with a Malaysian company accused of land grabbing in Papua New Guinea.
Oxfam Australia says the bank is among Australia's big four banks not living up to their image as leaders in sustainable banking.
In a new report Oxfam alleges Westpac has had a long term financing relationship with the logging company WTK Group, which was found by a PNG Commission of Inquiry to hold an invalid land lease.
Westpac says it welcomes Oxfam's report and it regards land grabbing as a serious issue which it addresses through responsible lending and banking practices.
But the bank says customer confidentiality means it can't comment on particular allegations made by Oxfam - including the acknowledgement of specific customer relationships.