Woolworths chief executive Amanda Bardwell is making major changes to the management of the company’s flagship supermarket division as it reworks its lucrative range of own-branded products and attempts to claw back market share lost to smaller rivals Coles and Aldi this year.

The long-serving head of supermarket and retail operations, Paul Harker, will take a sabbatical but remain at Woolworths, the company said in a notice to suppliers on Monday. Harker was the senior executive who appeared at a Senate inquiry that was considering whether Woolworths and Coles abused their market power and their control over prices.