Sen. Edward M. Kennedy (D-Mass.) told a hearing on national health insurance yesterday that any failure to enact a comprehensive health insurance measure "will bankrupt the American people."

Kennedy noted that 26 million Americans, almost 10 per cent of the population, have no health insurance and that the cost of health care continues to rise at twice the national inflation rate.

Kennedy has long supported enactment of a national health insurance plan.

Health, Education and Welfare Secretary Joseph A. Califano Jr., chairing an all-day hearing as part of his plan to come up with a health insurance proposal early next year, interrupted one witness who was about to attack the secretary's position on abortion.

Frederick S. Jaffe, representing a population-limitation group, was urging Califano to include payment of legal abortion under national health insurance.

"The only reason why anyone would propose to exclude these services is because there are important differences among religious groups ont ehmorality of certain fertility control services, particularly abortion," Jaffe said.

"Some citizens feel it is wrong for them to pay taxes or premiums to finance services they find objectionable."

Jaffe started to say that no one would propose a plan barring blood transfusions because Jehovah's Witnesses opposed them or a plan tailored to Christian Scientists' objections to medical care when Califano interrupted to ask a question on another subject. When he got his answer, Califano excused Jaffe as a witness.

Califano personally opposes abortion, as does President Carter, and has predicted that the adminstration's national health insurance proposal will exclude abortion funding.

Kennedy and Jaffe were among the first of about 75 witnesses scheduled to advise Califano on the plan he should recommend to Carter.

Witnesses were selected by HEW, and appeared to support comprehensive plans rathe rthen more limited proposals designed to protect only against the costs of catastrophic illness.

Representatives of labor unions, senior citizens' groups, religious organizations, consumer groups and civil rights organizations were on the witnesses list.

In addition, a few witnesses testifying as individuals were put on the schedule because they have "horror stories" to tell about the existing, largely private health care system, department sources said.