Section 20B(5)(a) in The Slum Areas (Improvement And Clearance) Act, 1956
(a)where there is a general law relating to the control- of rents in force in the area in which the building is situate, the authority to whom applications may be made for fixing of rents of buildings situate in that area; and for the purpose of determining the rent under this section that authority may exercise all or any of the powers it has under the said general law; and the provisions of such law including provisions relating to appeals shall apply accordingly;