Asda has defended its demands for special case sizes, saying costs should not increase significantly for its suppliers.
The retailer has told them that developing more suitable case sizes was its number one weapon to tackle poor product availability.
One leading branded product maker said: "It's Asda's number one topic, but Sainsbury has also been pushing for smaller cases to move through its convenience division. They are not setting deadlines yet -- but have made it clear that it's going to happen.
"They want case sizes more suited to store space allocation and product rate of sale. But it's not cost effective if they all want different things."
However, Asda's head of fresh merchandising Matt Frost said it was unlikely that the retailers would all plough divergent furrows.
Tesco's moves on shelf-ready packaging (see pages 25 and 31) would in many instances prompt manufacturers to look again at case sizes, he said.
At Asda, availability of cooked meats, one of the first categories to get new cases and shelf-ready packaging, had significantly improved, said Frost. Colour coding of cases to make products easier to find in shops' storerooms was also paying off.