A congressional panel, seeking to avoid another crisis like the recent cutoff of mortgage funds in the District of Columbia, began deliberations yesterday on possible reforms of the City Council's legally challenged use of its emergency lawmaking powers.

Mayor Marion Barry and City Council Chairman Arrington Dixon both insisted to a House District subcommitee that the city has not abused the emergency powers despite a recent Superior Court decision contending that it had.

Del. Walter E. Fauntroy (D-D.C.), who conducted the hearing, cited figures showing that the council passed 377 laws using its regular procedures and 361 using emergency procedures between January 1975, when the Home Rule Charter went into effect, and Dec. 1, 1979. It has passed 91 emergency laws so far this year.

Under the charter, regular legislation requires a time-consuming congressional review. The council can, however, declare an emergency and pass legislation that is valid for 90 days without such review.

Superior Court Judge George H. Revercomb ruled in October that the council acted illegally when it passed nearly identical emergency legislation twice, invoking and later extending a still-effective moratorium on condominium conversions. Emergency power can be used only once on a given issue, he said.

Since the city's mortgage interest ceiling of 15 percent had been raised by the similar passage of two successive emergency laws, the Federal National Mortgage Association and the Federal Home Loan Mortgage Corp. cut off funding of home loans in the city. Together they form the biggest single source of mortgage funds locally.

Congress hastily passed a law last month validating the 15 percent interest ceiling, ending the cutoff after three weeks.

Yesterday's hearing dealt chiefly with a bill sponsored by Fauntroy and others that would let the city pass emergency legislation valid for 180 days, but prohibit extensions. Barry and Dixon said they were dubious.

Rep. Stewart B. McKinney (R-Conn.) said he would propose an alternative -- a loosening of the congressional power to review D.C. legislation coupled with the elimination of the city's emergency powers. Under his proposal, the congressional D.C. committees would reserve the right to review council-passed bills they decide are of special interest to the federal government. Bills of strictly local concern would go into effect in seven days.

During the hearing, Barry remarked that officials of the Federal National Mortgage Association, which led the funds cutoff, apparently "read something in the paper and thought Judge Revercomb's order put (mortgage investments) in jeopardy . . . they overreacted."

Not so, said James E. Murray, the association's senior vice president and general counsel, who testified later. He said the decision, taken reluctantly, resulted from a serious legal review of Revercomb's decision initiated by the Philadelphia regional office and ratified at Washington headquarters.