The Hungarian-born restaurateur and critic warned that Ramsay and Oliver are "not as good as they used to be" because they have become focused on their burgeoning business empires.
"Ramsay and Oliver are not chefs any more, they are business people," Ronay told the Daily Telegraph. "They don't cook, they're interested in and concerned with money.
"Gordon Ramsay was a great chef, but he cannot be called a chef when he's not cooking. Sure, they've developed successfully from a business point of view, but not from a gastronomic point of view. It's a pity."
Ronay, who launched his first cookbook in 1957, said that the term "celebrity chef" is troubling, because it denotes cooks who have turned themselves into a brand.
"The most prominent celebrity chefs, as you like to call them, are not in very many cases chefs any more. I am worried about this trend.
"Celebrity chefs want to be talked about only because they want more business. Years ago the ambition was to cook better food, now it's to get a good balance sheet."
By Daniel Thomas
E-mail your comments to Daniel Thomas here.