Vice President Hubert H. Humphrey yesterday denounced the wave of riots which has swept U.S. cities and accused Congress of "lacking a sense of urgency" in solving the problems of the city.

Speaking in Boston at the 44th annual convention of the nation's Mayors, Humphrey said that "there can be no freedom, no equal opportunity, no social justice, in an environment of mob rule and criminal behavior."

But Humphrey said that Congress had been "inexcusably slow" in providing bills and appropriations which would substantially aid our cities.

The Vice President told the Mayors that the problems of urban slums were oppressive. He cited the inadequate collection of garbage, dirty streets, high crime rates and inadequate law enforcement, decrepit housing, and inadequate public transportation as some of the slum's major problems.

But he added that these problems "in no way justify riots, looting and arson." He continued: "But there can be no doubt that they provide the combustible environment in which a spark of criminal violence can burst into a flame of social disorder."