No commissioner or employee of an authority shall acquire any interest, direct or indirect, in any housing project or in any property included or planned to be included in any project, nor shall he have any interest, direct or indirect, in any contract or proposed contract for materials or services to be furnished or used in connection with any housing project. If any commissioner or employee of an authority owns or controls an interest, direct or indirect, in any property included or planned to be included in any housing project, he shall immediately disclose the same in writing to the authority, and such disclosure shall be entered upon the minutes of the authority. Failure to so disclose such interest shall constitute misconduct in office. However, no provision of this section shall be deemed to prohibit any bank, otherwise qualified, an officer, stockholder or employee of which is a commissioner of a local housing authority, from serving such housing authority as a depository bank or fiscal agent. Nothing contained in this section shall prevent commissioners of housing authorities of cities or towns of less than 2,500 population, according to the last or any subsequent decennial census of the United States, from entering into contracts to supply materials or services to be furnished or used in connection with said housing project, provided such contract is entered into as the result of a competitive bid submitted on an invitation advertised for not less than three days.