The country’s top competition regulator has made a rare intervention in a public hearing, questioning Woolworths and its former chief executive Brad Banducci about a decade-old presentation that suggested that the supermarket giant could choose how hard it vied with rivals.

Australian Competition and Consumer Commission chair Gina Cass-Gottlieb’s appearance at a public hearing investigating the market power of the major supermarkets came early in a lengthy questioning of Woolworths executives including Mr Banducci and his successor Amanda Bardwell.