Woolworths will funnel more than A$500 million ($516 million) into improving sales as it lags further behind supermarket rival Coles.
The company's supermarkets division reported a disappointing 3.4 per cent increase in sales for the half year, markedly weaker than Coles' sales growth of 5.3 per cent.
Woolworths has downgraded its full year profit guidance and its director of supermarkets and petrol, Tjeerd Jegen, has resigned.
Chief executive Grant O'Brien says the profit forecast has been downgraded so it can invest more into reducing its food and grocery prices. He says short-term profitability is being sacrificed for sustainable long-term growth and about A$500 million in cost savings will partly fund supermarket investment.
"All our efforts will be on restoring sales momentum and continuing to deliver profit growth," he said. "In the short term, our focus is on investment in cheaper prices and better service to customers."