Some of Australia's major banks revealed Thursday they are among 17 banks being sued in the US for alleged rate rigging.
National Australia Bank, ANZ Banking Group and Westpac Banking Corp have all been named in documents filed in New York by two US investment funds and an individual derivatives trader.
Reuters has also listed Commonwealth Bank of Australia as a subject of the claim but the bank has not confirmed this to City A.M.
The US lawsuit claims the lenders manipulated the bank bill swap rate, a benchmark used mainly in Australian markets to price a range of financial products, to better benefit their trading positions.
ANZ said it would be "vigorously" defending itself against the US claim. Meanwhile, Westpac noted, while it had not formally been served with any proceedings, it denied the allegations and planned on defending itself against any claim that should materialise.
National Australia Bank, ANZ and Westpac have all also been subject to civil action brought by the Australian Securities and Investments Commission (ASIC), again in relation to allegations of manipulating the bank bill swap reference rate.
Benchmark rate rigging actions have plagued lenders for sometime now. For example, in the UK, the Financial Conduct Authority (FCA) has fined banks over £750m for Libor and Euribor failings, and £1.4bn for foreign exchange failings.