The Secretary of the Interior, or his duly authorized representative, is authorized in his discretion, and upon application of the Indian owners, to issue patents in fee, to remove restrictions against alienation, and to approve conveyances, with respect to lands or interests in lands held by individual Indians under the provisions of the Act of June 18, 1934 (48 Stat. 984) [25 U.S.C. 5101 et seq.], or the Act of June 26, 1936 (49 Stat. 1967).