I found the link attached, it's from the Soviet Union Encyclopedia of 1979 so it might not at all be what you're after. According to the text municipal credit is credit extended to municipal economy and housing construction. It is "issued by municipal banks, municipal mortgage banks, municipal savings banks, deposit banks of the ministry of finance, life insurance companies, commercial banks, and credit construction associations" and it is used by local authorities.

If this fits your context my proposal would be something like "bank som tillhandahåller kommunkredit".