A global litigation funder on Tuesday said it would back a shareholder class action against Australia's biggest bank over alleged breaches of anti-money laundering laws.

Australia's financial intelligence agency AUSTRAC last month launched a civil case against Commonwealth Bank of Australia (CBA), alleging "serious and systemic non-compliance" of the laws involving thousands of transactions.

Funder IMF Bentham said the open class action, with the claim to be filed by law firm Maurice Blackburn in the Federal Court, would allege the bank neglected its disclosure obligations as a listed company.

It would also claim CBA made "misleading and deceptive public statements claiming performance... of its obligations under the (Anti-Money Laundering) Act", IMF added in a statement.

Maurice Blackburn believes it could become Australia's largest shareholder class action.

It would be open to those who bought stock in the bank, Australia's largest firm by market capitalisation, between mid-August 2015 -- when Maurice Blackburn claims the bank knew of its breaches -- and last month.

CBA has more than 800,000 shareholders, with millions more holding stock through pension funds, according to this year's annual report.

The announcement came a day after a shake-up of the CBA board, with three directors to leave and a former banker at rival Westpac, Robert Whitfield, appointed. 

Following scrutiny over the AUSTRAC action, CBA said in mid-August that chief executive Ian Narev would retire by the end of the 2018 financial year.

The board shake-up followed allegations reported by Sky News last week that CBA also failed to adequately monitor billions of dollars in global transactions, potentially falling foul of international regulators.

The Federal Court ruled Monday the bank would have to file its defence in the AUSTRAC case by December 15, with the agency to respond by March next year. The next hearing was set down for April.

The AUSTRAC case has prompted other Australian regulators to launch inquiries into the bank over its handling of the alleged breaches and its organisational culture.

Shares in CBA, which have slid since the launch of the AUSTRAC case, fell 0.40 percent to Aus$74.11 in Sydney on Tuesday.