Any noncompetent Indian to whom a patent containing restrictions against alienation has been issued for an allotment of land in severalty, under any law or treaty, or who may have an interest in any allotment by inheritance, may sell or convey all or any part of such allotment or such inherited interest on such terms and conditions and under such rules and regulations as the Secretary of the Interior may prescribe, and the proceeds derived therefrom shall be used for the benefit of the allottee or heir so disposing of his land or interest, under the supervision of the Commissioner of Indian Affairs; and any conveyance made hereunder and approved by the Secretary of the Interior shall convey full title to the land or interest so sold, the same as if fee-simple patent had been issued to the allottee.