The National Food Processors Association said the federal government should halt plantings of gene-altered crops for pharmaceuticals until it imposes tougher regulations to prevent future incidents.

"There should be no testing of this kind unless you can get 100 percent confinement and containment. The risk is too high," said Rhona Applebaum, the group's senior vice president of regulatory affairs.

The Grocery Manufacturers of America, whose members include major foodmakers such as General Mills Inc. , Kellogg Co. and Del Monte , said it was "deeply concerned by ProdiGene's reported conduct."

"We strongly urge the biotech industry to direct its substantial research capabilities into investigating the use of nonfood crops for the development of pharmaceuticals," said Karil Kochenderfer, the group's environment director.

Both industry groups are supporters of biotech foods such as corn engineered to repel pests or to produce a better quality crop. But they part company with the biotech industry when it comes to growing so-called "pharm-foods" next to crops destined for human or animal food.

Environmental groups and many European nations take a different view. They oppose all biotech plants, contending that not enough is yet known about their long-term safety for humans.

Although unwanted corn often sprouts in soybean fields, ProdiGene failed to pull out its bio-corn in Nebraska and removed it too late in Iowa, according to the U.S. Agriculture Department.

As a result, ProdiGene was ordered to destroy 155 acres of corn in Iowa and may have to buy 500,000 bushels of soybeans quarantined in Nebraska because of possible contamination.

"These incidents reaffirm the Grocery Manufacturers of America concerns about the use of food crops for the development of plant-made pharmaceuticals," Kochenderfer said.

Dow Chemical Co. and Monsanto Co. are among other companies field testing new crops with the aim of commercializing them in three years.

Bo Miller, biotechnology policy director for Dow Chemical, said the company planted its first pharmaceutical crop in the U.S. Southwest only this year. Next year, Dow will closely monitor the field for unwanted stray plants, he said.

Miller did not disclose how many acres were planted with the company's experimental pharma-corn variety. The company has said it plans to take "extraordinary measures" to control corn pollen, including mile-wide buffer zones, covering plants with special screens and timing the planting of a field so it is not fertile at the same time as neighboring crops.

"Planting in the U.S. Southwest has been part of our business model from the beginning," Miller said.

Only about 300 acres throughout the United States was planted with pharm-crops this year, according to the industry.

Last month, the Biotechnology Industry Organization announced its members would follow new voluntary guidelines to grow plant-produced pharmaceuticals outside the Midwest and Plains states.