Woolworths boss Brad Banducci says he's embarrassed by worker underpayments as bill hits $500 million

Woolworths chief executive Brad Banducci has forfeited his performance bonus as the supermarket giant returns $500 million in backpayments to underpaid workers. 

In handing down a 57 percent fall in full year profit to $1.16 billion , Mr Banducci said he was embarrassed about the underpayments as the company braces for a steep fine from the Fair Work Ombudsman.

Mr Banducci tells ABC's Peter Ryan he's bracing for a penalty from the Fair Work Ombudsman.