D.C. Mayor Marion S. Barry told Congress yesterday that the federal government should give the District as much as $600 million more for its unfunded pension plans than is provided in a bill that President Carter vetoed last fall as too costly.

Testifying before the House District Committee, which is considering legislation identical to the $1.1 billion proposal Carter rejected last Nov. 4, the mayor argued that the federal government should pay for that portion of the benefits accrued before the city got home rule in 1975 that will be paid upon retirement to current police officers, firefighters, teachers and judges.

The bill passed by Congress last year, and pending before it again, limits the federal responsibility to those District employes who retired before 1975.

The additional federal share sought by Barry would be offset partially by benefits changes also favored by the mayor, and by the concession that the city government is largely responsible for widespread abuses in granting tax-free disability retirements to an inordinate number of retirees.

In his veto message, the president pledged his support for future legislation "providing that provisions are included that fully remedy the problem of retirement abuses."

In the carrot-and-stick amendments suggested by the mayor, the city would agree to pick up that portion of disability pensions that is above the national average, which works out to 60 percent of police and fire benefits.

Barry told Rep. Ronald V. Dellums (D-Calif.) the District Committee chairman, that "impressive gains" have been made in reducing abuses. In 1969, for example, he said, 99 percent of all retiring public safety employes were granted disability pensions. Last years, only 44 percent of new retirements were attributed to disability, ranking the District below New York, Chicago, Detroit, Baltimore, Boston and New Orleans, the mayor said.

Thomas O'Brien, fiscal planning coordinator for the city budget office, estimated that year's delay caused by the president's veto, coupled with inflation, already has pushed up the liabilities of the unfunded pension plans from $900 million to $1.1 billion.

Barry also wants Congress to amend the legislation to allow the city government to institute tighter controls over pension for future employes whose benefits will be the sole responsibility of the city beginning in 1982.

In the future, Barry would prohibit retired uniformed employes from receiving double compensation if they are hired as civilian employes of the District or federal governments. He also would reduce minimum disability benefits from 40 percent to 25 percent for on-duty injuries, and from 30 percent to 15 percent for off-duty injuries.

For current public safety employes, the mayor proposed changes that "are intended to close loopholes or correct errors in deciding disability claims."

Among them are revoking disability benefits any time a recipient's outside earnings exceed a fixed amount; allowing the city to cut off disability benefits to employes who recover before age 60, instead of the present age 50, and eliminating the one-year period during which recovered employes now continue to draw disability benefits.