ANZ continues to co-operate with the corporate watchdog's investigation into alleged interest rate rigging but won't comment on speculation that it will soon face legal action.
The bank on Monday said it would not comment on "speculation" that it will be subject to a civil action by the Australian Securities and Investments Commission over alleged manipulation of the rate at which the banks lend money to each other.
An announcement is expected within weeks, according to the Australian Financial Review.
"In keeping with our longstanding policy, we are unable to comment on ASIC investigations, or on speculation concerning their outcome," ANZ said in a statement.
ASIC has been investigating major banks over the integrity of their past bank bill swap rate submissions since 2012.
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UBS, BNP Paribas and Royal Bank of Scotland have already acknowledged what ASIC called evidence of conduct seeking to influence the bank bill swap rate.
The trio of international banks also donated a total $2.6 million to independent financial literacy projects after agreeing to enforceable undertakings in relation to potential misconduct.
ASIC on Monday acknowledged its investigation into the bank bill swap rate but would not confirm ANZ's alleged involvement.
"ASIC has disclosed to various parliamentary committees it is investigating a number of large banks in relation to alleged manipulation of the crucial bank bill swap rate," ASIC spokesman Matthew Abbott said in a statement.
"This is a major investigation that goes to the heart of trust and confidence in our markets. The investigation is ongoing and ASIC is unable to go into any more detail at this stage."
The investigation echoes a similar probe into the London inter-bank lending rate following initial newspaper reports of manipulation in 2008.
Barclays' chief executive resigned after the British banking giant was fined about $400 million by various regulators for attempted manipulation of the so-called Libor and Euribor.
ANZ shares closed 36 cents, or 1.49 per cent, lower at $x$23.73.
