Washington - Most food manufacturers and distributors cannot identify the suppliers or recipients of their products despite federal rules that require them to do so, federal health investigators have found.

A quarter of the food facilities contacted by investigators as part of the study were not even aware that they were supposed to be able to trace their suppliers, according to a report by Daniel R. Levinson, the inspector general of the Department of Health and Human Services.

The report, expected to be made public Thursday, comes as President Obama and a bipartisan chorus of lawmakers have promised major changes to the nation's food-safety system.

And it may help explain why many small food makers continue to issue peanut-related recalls more than two months after the Peanut Corporation of America was identified as the source of a salmonella scare that has sickened at least 691 people and has been linked to 9 deaths. The New York Times obtained a copy of the report.

As late as Monday, the Food and Drug Administration formally asked Westco Fruit and Nuts Inc., based in Irvington, N.J., to recall all of its products containing peanuts made by the Peanut Corporation. Jacob Moradi, Westco's owner, could not be reached for comment, but he told ABC News that the F.D.A.'s recommended recall - the agency does not have the power to issue food recalls on its own - could ruin his company.

"They are asking me to commit suicide based on presumption," Mr. Moradi said in a broadcast interview. "They have shown no proof."

An F.D.A. official said Mr. Moradi hid from investigators at his plant.

On March 14, Jay Robb Enterprises of Carlsbad, Calif., announced a recall of peanut-butter-flavored JayBars. Alana Weber of Jay Robb said in an interview on Wednesday that although the company knew the peanuts in the bars came from the Peanut Corporation, it believed until recently that its bars were not part of the recall.

The inspector general recommended that the F.D.A. seek greater authority from Congress to require and ensure that food facilities maintain adequate records. In an official response in the report, the agency said that it largely agreed with the recommendations. Representative Rosa DeLauro, a Connecticut Democrat who is holding a hearing on Thursday where the report will be issued, said the recommendations would be included in reforms passed by Congress.

"Traceability is a critical tool in our ability to identify the source of a food-borne illness outbreak and locate where contaminated products were sold," Ms. DeLauro said Wednesday.

To test compliance with the rules, federal investigators bought 40 products - including tomatoes, oatmeal and yogurt - from retail stores in New York, San Francisco, Chicago and Washington and tried to trace them to farms or to the border. Foreign firms are not required to maintain supplier records.

Investigators successfully traced the source for only 5 of the 40 products, the report stated. Three of the traced products were egg cartons whose supply chain included only a farm and a retailer. For a tomato, a bag of ice, a bottle of fruit juice and a bottle of water, investigators were not able to even guess the product's supply chain. For 31 other products, investigators were able to identify only the likely suppliers.

The investigators contacted 220 food facilities to ask about their supplier records. But only 118 of these businesses were included in the study because the rest were not required under rules adopted by the F.D.A. in 2005 to maintain supplier and recipient records. Of those 118 firms, 70 failed to provide investigators with required information about suppliers or customers, with 6 of the companies failing to provide any information at all.

One vendor told investigators that it kept no records of tomato purchases. Tomatoes have repeatedly been implicated in nationwide food contamination scares, including one last year. Fifteen facilities told investigators they mixed raw products from more than 10 farms.

"According to an estimate from a manager at a grain storage facility, if grain from one farm were contaminated, millions of bags of flour would be at risk and might have to be removed from retail shelves," the report stated.