Flooding cut the rail line and highway through the Nullabor in March, delaying stock deliveries to the west and leaving some supermarket shelves bare for weeks.
Woolworths Group chief executive Brad Banducci told a Senate committee into supermarket pricing on Tuesday it would be at least another 10 days until supplies returned to normal.
"For all of our Western Australian shoppers, there are still material issues in supply there," he said.
"We're working very hard, and I know our competitors are, to get them back into supply."
In a statement, a Woolworths spokeswoman said the supermarket giant was working to return supply levels to normal and a large amount of stock had been sent to WA after the rail line reopened.
"Our priority is getting more chilled products to our stores - things like cheese, margarine and juice, as well as meat and poultry items," she said.
"This week alone, our WA stores are receiving over a hundred thousand more cartons of chilled products than they usually would to help replenish stock levels."
A Coles spokesman said the company was working with suppliers to get deliveries into the state by road and rail.
"With the railway now reopened into WA, we have stock on its way into the state for our teams to replenish our stores," he said.
"As the backlog of deliveries via rail clears, customers can expect to see increased stock arrivals in stores over the coming days."
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