The Food and Drug Administration will try again in May to remove saccharin from the nation's diet foods and beverages because agency scientists remain convinced it may cause cancers, FDA Commissioner Donale Kennedy said yesterday.

He spoke in an interview after a panel of the National Academy of Sciences, asked by Congress to review saccharin policy, recommended a new food law that would give FDA authority to leave saccharin partly or wholly on the market if it found that benefits outweigh risks for any part of the population.

Kennedy, a biologist who came to the FDA in April 1977 from a Stanford University professorship, proposed saccharin's ultimate removal from food and drinks as one of his first acts in office. He proposed to allow only over-the-counter saccharin sales, so dieters or diabetics could add it to their food or beverages.

Congress, asked by hundreds of voters and the American Diabetes Association to leave the drug in diet foods and drinks, declared an 18-month moratorium on the ban and asked the science academy to review all food law and policy. That moratorium ends in May.

Kennedy said yesterday that he is still required to ban saccharin by the 1958 Delaney amendment to the food law. It flatly bars from the food supply any substance that causes cancer in man or animals.

Also, Kennedy said:

Other parts of the food law require saccharin's removal.

He considers it unsafe, no matter what laws say.

He believes any good food safety law would require saccharin's removal from foods, and society would not be wise to write a future law that would regularly allow the addition to food of substances as dangerous.

Under present law, he said, every food additive has to be shown to be safe, and saccharin was removed from a list of foods generally recognized as safe because of questions about its safety.

"It is now clear from animal stuides that it causes cancer in animals," he said. "On cancer in humans, the evidence is divided. The one study that did show [some human bladder cancers] was the largest and best-designed of the studies available. But there are other studies in progress, and we'll have to see what happens."

Meanwhile, he said, FDA soon will probably propose a much less sweeping change and more "a fine tuning" of present food law to deal with some problem, rather than adopt the change the science academy panel recommended.

It is probable, however, Kennedy has also said recently, that FDA will ask for a relaxation of the strict Delaney clause. It would do so, he said, to allow continued use of some toxic substances "in a very small number of cases" where benefits may outweigh risks.

In a statement distributed at a science academy news conference yesterday, Kennedy called the academy panel's position a useful starting point for debate, but one certain to be considered controversial.

His views made it clear that he will hardly echo all the panel's views, while agreeing with some of its recommendations, such as authority for FDA to consider both risks and benefits of an additive.

The panel recommended a thorough overhaul of U.S. food safety policy to end what it called the rigidity of present law, and give federal regulators discretion to ban, partly ban or approve foods or additives.

The panel said regulators should be able to use their own judgment, based on the best available scientific knowledge, to classify a doubtful substance as either high, moderate or low-risk.

In each case, including that of saccharin, the regulators would still be free to ban the substance, ban it for some persons while approving it for others or allow its sale but require warning labels and an educational drive to minimize use.

On saccharin, the panel said there is no scientific evidence to show direct benefits to health, but neither can anyone say saccharin does not help dieters or diabetics control their intake of sweets.

It called saccharin a cancer-causer of "low potency," but one that may also promote the cancer-causing effects of other compounds. It said saccharin should therefore be judged either a high- or moderate-risk compound, but not be totally banned.

Still, the panel made no specific recommendation, giving Congress a series of options from a total ban to none at all.

Most important, said the committee, Congress should not act on saccharin alone, but move to establish an overall new food policy to end present confusion.