Notwithstanding anything to the contrary in , any oil or gas lease issued under the authority of this chapter may be assigned or subleased, as to all or part of the acreage included therein, subject to final approval by the Secretary and as to either a divided or undivided interest therein, to any person or persons qualified to own a lease under this chapter, and any assignment or sublease shall take effect as of the first day of the lease month following the date of filing in the proper land office of three original executed counterparts thereof, together with any required bond and proof of the qualification under this chapter of the assignee or sublessee to take or hold such lease or interest therein. Until such approval, however, the assignor or sublessor and his surety shall continue to be responsible for the performance of any and all obligations as if no assignment or sublease had been executed. The Secretary shall disapprove the assignment or sublease only for lack of qualification of the assignee or sublessee or for lack of sufficient bond: , That the Secretary may, in his discretion, disapprove an assignment of any of the following, unless the assignment constitutes the entire lease or is demonstrated to further the development of oil and gas:

((1)) A separate zone or deposit under any lease.

((2)) A part of a legal subdivision.

((3)) Less than 640 acres outside Alaska or of less than 2,560 acres within Alaska.