Australia's banks took "decisive action" to disrupt the financial flows supporting the country's illicit tobacco trade after Austrac and the Illicit Tobacco and E-Cigarette (ITEC) Commissioner asked them to strengthen monitoring and reporting under their existing anti-money laundering and counter-terrorism financing obligations, the regulator said in a Tuesday statement.

They asked lenders to scrutinize high-risk transactions linked to tobacco retailers, including cash deposits and EFTPOS activity, according to Austrac Chief Executive Brendan Thomas.

Almost 90% of banks and authorized deposit taking institutions responded to Austrac's request, per the statement, and around 20% of the reporting entities exited high-risk customers with exposure to illicit tobacco, while others imposed enhanced controls and monitoring arrangements to manage identified risks.

Commonwealth Bank of Australia's (ASX:CBA) shares gained about 1% in recent Tuesday trade, ANZ Group Holdings' (ASX:ANZ, NZE:ANZ) Australia shares shed 1%, and Westpac Banking's (ASX:WBC, NZE:WBC) Australia shares fell 2%.