For the second time in as many weeks, the Federal Trade Commission has taken on the American Medical Association.

The FTC staff yesterday attacked the continuing domination by the AMA of the Liaison Committee on Medical Education (LCME) -- the accrediting body which determines medical scholls' eligibility for federal funds.

The AMA, which designates six of the 15 members of the LCME, "has a possible conflict of interest," according to the FTC staff, because it is responsible for the "economic interests" of its member doctors, and can further that interest by limiting the number of new doctors.

Critics have argued that by blocking the accreditation of new medical schools which are needed to increase the number of new doctors, the AMA has been able to keep incomes high among its members by limiting the supply of doctors.

The FTC staff was also critical of the involvement of another trade group, the Association of American Medical Colleges, which designates another six members of the LCME.

The AMA and the AAMC fund the LCMEs operations, and the AMA House of Delegates exercises veto power over any decisions of the LCME.

The FTC Bureau of Competition staff made its comments in a letter to the Office of Education, which last year ordered the LCME to become autonomous from the AMA.

At that time the Office of Education pointed out that the LCME was too dependent on the AMA, and would have to break that relationship in order to comply with federal laws governing accrediting bodies.

In 1977 the Office of Education directed the LCME to file an interim report on its progress in meeting the concerns -- particularly the relationship with the AMA -- expressed by both that office and the FTC. Yesterday's FTC blast came in response to that interim report, filed earlier this year by the LCME.

"The fact that LCME's interim report was prepared on AMA stationery does not inspire confidence that this concern was fully appreciated," wrote FTC official Alan Palmer to the Office of Education.