''Technically, crude fiber labeling is in compliance with current F.D.A. regulations,'' said Fred Shank, deputy director of the F.D.A.'s office of nutrition and food sciences. ''I think we have a problem when the companies are using crude fiber measurements to say that their bread has 400 percent more fiber.''

''We recognize that science had gone beyond crude fiber,'' he said, ''and through our proposal, correspondence with some of these companies, they know we support dietary fiber as a method of measurement. But to say that our policy is less than clear is no understatement.'' Mr. Shank said that the regulation has not become final because it does not have a high priority at F.D.A.

In 1979 the Federal Trade Commission charged ITT-Continental Baking Company with false and misleading advertising because it had not disclosed that the alpha cellulose in its bread Fresh Horizons came from wood pulp. The F.T.C. also said that high fiber claims for Fresh Horizons, similar to those being made for the breads available today, were inaccurate. ITT signed a consent agreement with the F.T.C. that required the company to include the following statement in all of its advertising for Fresh Horizons or other bread products containing wood: ''The source of (this/the) fiber is wood.''

The F.T.C. said the failure to identify the fiber source was misleading because ''consumers would not expect to find fiber derived from wood as an ingredient in a bread.''

In addition, the ruling prohibited the company ''from making claims about comparative amounts of fiber in food products unless the comparisons are based on a scientific method of measurement.'' The F.T.C. said such claims must be based on a measurement of dietary fiber.