BATTLE CREEK, Mich. (AP) _ It may be a case of sour grapes but Kellogg Co. insists its competitor is misrepresenting its raisins.

Kellogg said Tuesday it has filed a lawsuit in U.S. District Court in Kalamazoo charging General Foods Corp. and its advertising agency, Grey Advertising Inc., with running misleading ads about the quality of raisins in their breakfast cereals.

The suit charges that General Foods altered and improved the appearance of its raisins by cleaning off ''extraneous materials such as cereal parts'' from the Post Natural Raisin Bran Cereal before it was photographed next to their Kellogg counterparts, said Neil Nyberg of Kellogg.

''The copy (in the ads) also talks about Post not having sugar on its raisins, when the facts are both products contain the same amount of sugar,'' Nyberg said. He said both cereals contain 9 grams of sugar in each ounce of cereal.

The suit does not specify damages but seeks corrective advertising, a permanent injunction against future misleading ads and punitive damages of $100 million.

Asked for a response, Jack Whiteman, a spokesman for General Foods in White Plains, N.Y., said, ''The lawyers haven't even read it yet. Before there's anything to say, we have got to digest it.''