ANZ Banking Group chairman David Gonski said the corporate regulator shouldn't be the culture police after it launched a $100 million case against his bank for allegedly manipulating the Bank Bill Swap rate.

Insiders said Australian Securities and Investments Commission chairman Greg Medcraft, whose term expires in May, has hardened his line in the "culture wars" in the wake of the Commonwealth Bank of Australia's financial planning scandal and the more-recently sacked ANZ traders.