Lockdowns through the course of the year and mandatory staff isolations blew up expenses for Woolworths and its smaller rival Coles Group, while bad weather and floods have blocked roads and wiped out crops, increasing wholesale costs.

The cost of doing business, excluding one-off expenses, increased 96 basis points to 25.1% for Australian Food in the reported period.

"We expect the trading environment to remain volatile and challenging due to endemic COVID disruptions, ongoing supply chain challenges, higher costs across our business and cost-of-living pressures for our customers," the company said.

Total sales at the Australian Food business for the first eight weeks of fiscal 2023 were down 0.5% on the prior year. Sales in its New Zealand Food segment were down 1% during the same period.

Australia's largest supermarket chain, however, said COVID-related costs are expected to substantially decline in fiscal 2023 as customer behaviours continue to normalise.

Rising prices and the cost-of-living crisis have prompted consumers to cut discretionary spending in favour of essential goods such as groceries.

Some customers are trading down from beef into more affordable sources of protein and trade across from fresh vegetables into more affordable frozen and canned offerings, Woolworths said.

The company posted annual net profit after tax from continuing operations, excluding items, of A$1.51 billion ($1.04 billion), compared with A$1.50 billion a year ago.

Australia's second-biggest grocer Coles posted an estimate-beating annual profit on Wednesday, as it reined in spending amid surging inflation, but warned of persistent cost pressure.

($1 = 1.4478 Australian dollars)

(Reporting by Harish Sridharan and Savyata Mishra in Bengaluru; Editing by Vinay Dwivedi and Sherry Jacob-Phillips)