Federal cuts in the program to immunize children against diseases such as polio, measles and mumps could lead to new outbreaks of illness costing far more in additional health care expenses, medical experts told Congress yesterday.

"If the program is not maintained, we can expect a resurgence of disease," warned Dr. Frederick Robbins, who heads the Institute of Medicine here and won a Nobel Prize for his contribution to the polio vaccine. Immunization is not only "effective and safe in protecting our children against disease, disability, misery and death," but "cost effective," he said.

"It is rare to find a medical intervention that actually saves money in addition to relieving suffering. These childhood immunizations are that rare case," said Dr. H. David Banta of the congressional Office of Technology Assessment.

Rep. Henry A. Waxman (D-Calif.), who chairs the House Energy and Commerce health subcommittee, noted that the Reagan administration last year proposed cutting back federal immunization funds by 34 percent. While the 1982 budget is not final, he said the congressional resolution now in effect amounts to a 10 percent reduction in the program.

This, in combination with sharp increases in vaccine costs, could mean a one-third cut in the number of children immunized with federal funds this year, Waxman said.

Following a federal initiative by the Carter administration, immunization levels for school-age children rose to over 90 percent for routine vaccinations. These include protection against diphtheria, whooping cough, tetanus, polio, measles, rubella (German measles) and mumps.

There were fewer than 10 cases of polio in 1980 and measles cases have dropped by 99 percent since the vaccine became available in the 1960s.

Officials from the federal Centers for Disease Control said afterward that they were hopeful that the states would maintain the effort but concerned that they might reduce their programs proportionately.

"Based on past history, anytime you reduce federal involvement in this type of program, the states and others reduce their programs proportionately," said one CDC expert.

A California health official, Dr. James Chin, agreed, saying that "the announced federal reductions have already resulted in large cutbacks in state and local programs which have had to make plans based on the worst contingencies."