Coles chief executive Leah Weckert says keeping supermarket shelf prices down will require the cooperation of suppliers to ensure customers, who are shopping around more than ever, get a good grocery deal.

Ms Weckert, who was hauled before a Senate inquiry earlier in April along with outgoing Woolworths boss Brad Banducci, said suppliers and Coles would need to help fund discounts to lift sales volumes, which remains in positive territory.