Excessive levels of harmful compounds could show up in genetically engineered foods because the government has failed to put strong safeguards in place to catch them, a consumer group says in a report scheduled for release today.

The Center for Science in the Public Interest (CSPI), a Washington group known for a moderate stance on the use of genetic engineering to alter food plants, contends that the Food and Drug Administration, the primary federal agency responsible for food safety, missed "obvious errors" in reviewing some gene-altered crops. Although crops now on the market appear to be safe to eat, the group said the FDA's procedures are so full of holes that continued safety cannot be ensured as companies press to bring many more genetically engineered plants to market.

"The companies don't provide enough data to prove these foods are safe," said Gregory A. Jaffe, director of biotechnology issues at the center. "And FDA's review process doesn't give you a lot of comfort that they've looked at it closely and challenged the companies."

Laura Tarantino, deputy director of food-additive safety at the FDA, rejected the group's contentions, saying companies have provided all the data on their crops that the agency deemed important. She said FDA staffers were well aware of the possibility that genetic engineering could increase levels of harmful compounds in food. She called this a "very hypothetical risk" and said she did not believe it had happened with any crop now on the market. She added, however, that the FDA was studying whether it should make changes in the way it reviews such foods as more move toward commercialization.

The food-processing industry also rejected the report's conclusions, saying the current regulatory setup gives the FDA maximum "flexibility" to ensure that foods are safe.

The center's report is designed to influence an unfolding public debate about the way the nation regulates genetically altered crops. At the request of the FDA and other federal agencies, a panel of the National Academy of Sciences, meeting today in Washington, is studying whether such crops could have unintended consequences for human nutrition.

Much of the concern centers on "anti-nutrients," or harmful compounds common in many food crops. Typically such compounds are present only at minuscule levels. But when crops are genetically altered there is at least a theoretical risk that the level of anti-nutrients could increase, making consumption of that plant more harmful. The FDA has failed to establish firm procedures requiring companies to test for such harmful changes, the report said.

The center said the FDA's review process is an outgrowth of the nation's lax approach to dealing with genetically altered crops. Congress has never passed a law to regulate plants or animals created through genetic engineering, and, as a result, federal agencies have had to stretch old laws, written for other purposes, to create a patchwork system of rules.

Some gene-altered food plants, particularly if they contain foreign genes to help them fight bugs, fall under regulations requiring their creators to get mandatory approval from the Environmental Protection Agency before going to market. But others fall solely under the FDA's food-safety jurisdiction, and that agency has adopted only voluntary procedures for companies to follow in assuring the public their products are safe.

The food industry likes this voluntary system. Environmental groups, suspicious of all genetic manipulation of plants or animals, have long decried it. CSPI is one of the few consumer-oriented groups that supports genetic manipulation in principle but argues that the voluntary system must be scrapped.

For the report, CSPI reviewers studied about a quarter of all the cases where gene-altered plants have come before the FDA for review. In many instances, the report said, the FDA requested information on the nutritional composition of a plant that industry failed to provide. In three of 14 cases, CSPI reviewers found "obvious errors" in FDA analyses of certain food crops. For instance, certain scientific papers -- cited to prove that human exposure to a particular foreign protein in gene-altered tomatoes and cantaloupes was safe -- don't actually prove anything of the sort, the center said. "Had FDA conducted thorough reviews, the errors would have been easily detected," the report said.

Tarantino of the FDA said she had not seen the CSPI report and could not respond to the claim. But there is routine give-and-take between the FDA and companies about the quality of scientific evidence, she added, and the agency will not bless crops for commercialization until it is satisfied.

CSPI called for a tighter system involving mandatory review of new products and a detailed statistical analysis of risks -- in essence, a version of the rigorous drug-approval process for which the FDA is widely respected.

Timothy Willard, a spokesman for the National Food Processors Association, said the food industry would support some changes, including making some type of FDA review mandatory. But he noted that no company has opted out of the current voluntary process, which has worked to date.