The federal government worried by "intolerably high levels" of unneeded surgery, will begin paying for second medical opinions for Medicare patients before surgery is done, a top federal health official said yesterday.

Health Education and Welfare Under Secretary Hale Champion announcing a new "major effort" to combat unnecessary operations, also urged all Americans to get a second opinion before any surgery except in emergencies.

Appearing before the House Oversight and Investigations Subcommittee, he congratulated that body and Chairman John E. Moss (D-Calif.) for publicizing the problem for three years. Then he became the first HEW official to acknowledge before the committee that "there is too much" unnecessary surgery and to attack HEW's past "unresponsiveness."

Champion did not try to estimate how much unneeded surgery thre is nationally. Experts say there are no good nationwide studies.

But he said that in some cities there is up to 200 per cent more use of commonly abused procedures like hysterectomies than in immediately neighboring communities, and that the nation's overall surgery rate increased by 25 per cent between 1970 and 1975.

HEW lawyers are now removing some legal barriers to allow Medicare patients to have second opinions if they want them before surgery, be reported.

If two doctors disagree. HEW will pay for a third opinion if the patient wants it, an HEW spokesman said. If the patient wants an operation despite an adverse second opinion, HEW will still pay for it if it's found appropriate by a hospital's unusal standards, the spokesman added.

Among other actions to cut down on excess operations. Champion said HEW will also:

Ask the nation's 132 "professional standards review organizations" (PSROs) - groups of doctors who monitor hospital admissions - to "move agressively" into reviewing surgical services.

In cities where there is too much surgery, require PSROs to begin reviewing operations before they can be performed.

Strengthen the PSRO system by monitoring PSROss more closely, helping them correct deficiencies and requiring them to identify and discipline doctors whose practices are substandard.

With the aid of "distinguished medical consultants," develop "specific and measurable" criteria - or medical indications - to guide PSROs in judging particular operations' necessity.

Identify obsolete or otherwise questionable procedures and stop paying for them under federal programs.

"Cut back significantly" on the number of surgeons trained at public expense, since "surgeons, as you might expect, favor a surgicial approach to medical problems," and "excess surgeons lead to excess surgery."

As Champion spoke, HEW Secretary Jospeh A. Califano Jr. told the House Health Subcommittee of another problem that contibutes to runaway health costs: fraud by doctors and patients in Medical and Medicaid programs.

He said HEW now estimates that Medicaid fraud alone cost federal and state governments more than $2 billion in the fiscal year that ended Sept. 30.

But he reported progress in reducing Medicaid use by persons who are financially ineligible because they earn more money than various states set for eligibility for this program for the medically indigent.

Nationally, he said, 8.6 per cent of all payments on behalf of Medicaid patients were in error in the past year, in one case in three because of the client's misrepresentation in two cases because of the state agency's error.

He said this figure is down four-tenths of a per cent from the year before, and he described a federal-state program to cut mistaken payments by 1 per cent a year over the next three years to save more than $2 billion.

In Washington, the previously reported error rate was 47.9 per cent higher than any state's. The Maryland figure was 13 per cent, Virginia's 7 per cent.