WASHINGTON (Reuters) - U.S. consumer and environmental groups urged Campbell Soup Co. (CPB.N) on Wednesday to stop using gene-spliced ingredients in its soups, breads, juices and other products as part of a new campaign targeting major food makers.

Greenpeace, Friends of the Earth, the Center for Food Safety and four other groups said they aimed to deluge the companies with thousands of letters, e-mails and telephone calls from American consumers worried about the lack of safety testing and labels on foods containing gene-altered crops.

A similar public outpouring is being orchestrated at the Food and Drug Administration, which is due to propose new regulations for genetically altered foods in September.

Campbell Soup, the world's biggest maker of soups, is the first company targeted by the coalition. The New Jersey-based firm licensed the first genetically modified food -- the Flavr Savr tomato, which was engineered for a longer shelf life.

"Campbell Soup is an American icon," said Rep. Dennis Kucinich. "People are largely unaware that the food they are eating is genetically engineered," said the Ohio Democrat, who supports the new campaign and has sponsored legislation to require labels on biotech foods.

Campbell also makes Pepperidge Farm breads and cookies, Prego pasta sauce, V8 juice, and Godiva chocolates.

A spokesman for Campbell Soup was not immediately available to comment.

OTHER FIRMS TO BE TARGETED

"I think you will see consumers by the millions go after these companies," said Andy Kimbrell, director of the Center for Food Safety, a consumer group that has pressed for strict safety testing and mandatory labels.

"What we're hoping for is the same kind of public response that happened at the U.S. Agriculture Department with its organic food label rule-making," Kimbrell said. Other major companies will be targeted over the next six months, he said.

The USDA was forced to take another look at organic food labels after receiving an unprecedented 275,000 letters from consumers who didn't want genetically modified crops or those fertilized with sewage sludge to carry the label.

The green and consumer groups contend that most Americans are simply unaware that roughly 60 percent of the foods on grocery store shelves contain gene-spliced corn, soybeans and other vegetables. It also contends that the FDA is not doing enough to protect Americans from potential health and environmental risks.

A coalition of agribusinesses, farm groups and food industry groups launched a $50 million campaign earlier this year to persuade consumers that biotech foods are safe. They contend that thousands of tests conducted by companies over the past decade demonstrate gene-altered foods are no different than conventional ones.

Genetically altered crops typically have a gene inserted to help fight pests or disease. Biotech crops in development aim to add nutritional benefits to the plant.

The biotech food fight in the United States is especially crucial now that Britain, France, Japan and a dozen other countries have already restricted or banned gene-spliced foods at the behest of consumers.

The issue will be on the agenda of the Group of Eight nations meeting in Okinawa later this week. The world's richest nations plus Russia plan to try and agree on a framework for research and study of biotech foods.

A GROWING CONCERN

In Washington, the FDA is preparing regulations that will require food makers to have mandatory consultations with agency scientists before a biotech food can go on the market. The FDA also is trying to make more information available to consumers via its Web site.

"It is very clear to us that there are a growing number of consumers who are concerned about these products," Jim Maryanski, FDA biotech foods coordinator, said in an interview.

"The FDA's job is to make sure the products are safe and the science is right," he said. "Ultimately it is the consumer who will decide if the products survive or don't."

In April, a National Academy of Sciences study cautiously endorsed the safety of biofoods but urged U.S. agencies regulating them to do more to protect the environment, as well as undertake long-term monitoring of health effects.

American farmers this year slightly reduced their plantings of altered crops for the first time, but more than half of U.S. soybeans and one-fourth of corn will still be grown with bioengineered varieties.

Farmers, meanwhile, have a mixed view of the food fight.

"I envision myself some day growing 40 acres of a genetically altered crop that will be marketed to a drug company and will make a big difference in the health of people," said Vic Riddle, an Illinois corn grower. "There is a lot of potential with these crops that we can't even imagine yet."