WASHINGTON (Reuters) - The National Academy of Sciences cautiously endorsed the safety of biofoods on Wednesday, but urged U.S. agencies that regulate genetically altered plants to do more to protect health and the environment.

In a long-awaited study that is expected to influence the U.S. policy debate over whether biofoods need more stringent regulation, the Academy emphasized no evidence existed to suggest that biofoods were unsafe. But it also called for more research into health risks for humans and for long-term monitoring of crops to detect any adverse impacts on wildlife.

The 260-page report was immediately criticized as biased by two Congressmen and some environmental and consumer groups, who contend that half the members of the science panel had financial links to the biotech industry. The food industry hailed the study as confirming its view that potato chips, puddings, salad dressings and other foods made with altered crops are harmless.

Fearful of a consumer backlash similar to what happened in Europe, the agribusiness industry this week launched a $50 million public relations campaign to persuade Americans that gene-spliced crops have benefits that have been overlooked.

Several U.S. green and consumer groups, however, have pressed the government to require more testing and subject altered crops to the same strict standards as pharmaceuticals.

Report Says Research Needed

The National Academy of Sciences report took a carefully-crafted view, calling for more research into several complicated issues. It did not address biofood labeling

or international trade issues.

``Public acceptance of these foods ultimately depends on the credibility of the testing and regulatory process,'' said Perry Adkisson, chancellor emeritus at Texas A & M University and the head of the National Academy of Sciences panel.

``The federal agencies responsible for regulating transgenic plants have generally done a good job,'' he said. ``Given the current level of public concern and following our review of the data, it is the committee's belief that the agencies must bolster the mechanisms they use to protect human health and the environment.''

As the report was unveiled, two dozen demonstrators wearing white lab coats marched outside the academy's headquarters to protest industry ties of some of the study's authors.

The protesters complained that one of the original members of the panel resigned to take a job with the Biotechnology Industry Organization, a trade group. Four scientists on the panel received research funds from the industry, and a lawyer on the committee represents biotech companies.

Top executives of the National Academy of Sciences, which is often called upon by cabinet members or Congress to sort out thorny scientific issues, insisted the report was fair.

``We stand behind the committee we appointed,'' said E.W. Colglazier, chairman of the academy. ``We feel they have done a very credible and independent job.''

Food and agribusiness groups said they welcomed the report, which used science to examine the biofoods issue.

``The findings by the NAS solidify the fact that sound science and common sense should continue to guide the U.S. regulatory approach to biotechnology,'' said Stacey Zawel, a vice president of the Grocery Manufacturers of America.

The report also backed up industry's claim that altered crops can reduce use of pesticides, said Val Giddings, a vice president of Biotechnology Industry Organization.

Usda, Fda, Epa Need Better Coordination

Jane Rissler, a critic of biotech crops with the Union of Concerned Scientists, said the report broke new ground.

``This is an acknowledgment that there are risks and a need to strengthen regulations,'' Rissler said. The report also substantiated her contention that the USDA does not require enough experimental data from companies on such issues as whether genes flow into other species, she said.

But Rissler disagreed with the panel's finding that biofoods are safe because no evidence exists to indicate otherwise. ''There has not been enough research by anybody looking at possible harm. Absence of evidence does not mean absence of harm,'' she said.

The academy scientists urged the U.S. Environmental Protection Agency, Agriculture Department and Food and Drug Administration to ``quickly come to an agreement'' on each agency's role in regulating gene-spliced plants.

The scientists took no position on the controversial laboratory study issued last summer by Cornell researchers indicating that monarch butterflies were hurt by pollen from Bt corn, a variety engineered to resist a destructive bug.

The issue needs more research, including ``rigorous'' field evaluations and testing to see if the same results occur in actual farm fields, the panel said.

``The committee did not identify anything that we would call a mistake,'' said Stanley Abramson, a Washington attorney on the panel. ``Our recommendations are designed to help the EPA and its sister agencies do a better job.''

Last year, American farmers grew more than 70 million acres (28 million hectares) of transgenic crops such as Bt corn and Roundup Ready soybeans, a variety treated to resist a widely used weedkiller. Plantings will drop slightly this year for the first time since 1995, according to the USDA.

The academy's investigation grew out of a battle over the EPA's attempt to regulate plants engineered to protect against destructive bugs. The agency should finalize its rules, first proposed in 1994, that are aimed at preventing plants from crossbreeding and creating super-weeds, the report said.