Australia's food and grocery prices have to come down further because they are "crazy" compared to the rest of the world, Coles managing director John Durkan says.

"It's already an overpriced grocery market in my view and I've been saying that for nine years," Mr Durkan told analysts during Wesfarmers' strategy day meeting on Wednesday.

"I still look at products here that are made overseas and they are crazy prices."

He said the cost of those products meant there was room for Coles' private labelled products to grow.