Rep. Stewart B. McKinney (R-Conn.) yesterday questioned the competence of the National Institute of Mental Health to monitor state mental hospital standards when the one facility it operates directly - St. Elizabeths Hospital here - is unaccredited.

"We've given these people the mandate to run every mental hospital in the country with federal participation, and here they can't even run their own."McKinney said during questioning of Department of Health, Education and Welfare officials.

McKinney emphasized repeatedly, and with some exasperation, the hospital's unaccredited status during hearings before the House District Subcommittee on Fiscal and Government Affairs.

The subcommittee is considering a bill to place St. Elizabeths under an independent corporation as an interim solution to the long unsuccessful attempts to transfer the hospital fromNIMB to city government control .

Federal and city officials who testified all opposed the corporation measure, or qualified their approval with demands for re-accreditation and other improvements before the facility is transferred.

James F. Dickson III, acting assistant secretary for health at HEW, said the bill would fragment and delay improvement plans and service to District of Columbia residents, who make up more than 85 percent of St. Elizabeth's population.

Appearing together before the panel,City Councilwoman Polly Shackleton and Albert Russo, acting director of the D.C. Department of Human Resources, called for assurances of federal funding before NIMB relinquishes control of the hospital.

The corporation bill authorizes $194 million in federal support for construction and $284 million operating expenses through 1982, but it mandates increasing District financing of the hospital.

NIMB would have to spend about $75 million to make improvementnecessary for re-accreditation, according to Betram S. Brown, director of NIMB.

"We would like to see more funds, but directed toward community-based programs," said John L. Johnson, president of the D.C. Mental Health Association, who opposed the corporation proposal.

Johnson said merly transferring the hospital is no solution to problems of "old and inadequate building, retention of people who do not require 24-hour hospitalization, poor staff morale, and lack of coordination" with DHR mental-health programs.

In addition to accreditation and other troubles, the General Accounting Office on Monday cited St. Elizabeths as seriously deficient in administration.

Acting St. Elizabeths Supt. Roger Peele, in commenting yesterday on the GAO findings, defended St. Elizabeths as an institution that provides care "as efficient or more that others" but at lower costs than private and military hospitals.

"It's a disgrace, we agree on that," McKinney told one group of witnesses. "We're stuck with trying to find somewhere where we can mandate that something be done."