§ 64. Payment of liens and encumbrances. Whenever a person would be entitled to the payment of any advance under section sixty-three of this chapter and there shall exist mortgages or other prior liens on such property, the holder of any such prior lien may apply to the city for payment of his mortgage or encumbrance. If after five days' written notice given by the corporation counsel to the owner of such property to file a verified statement of his objections, if any, to the payment of such mortgage or lien, the corporation counsel shall be satisfied as to the amount due to such mortgagee or lienor, and shall so certify, the city shall, to the extent of the moneys available under such section sixty-three, after providing for prior liens or encumbrances, if any, pay such mortgage or lien with the interest due thereon.