In accordance with part 3480 of this title, each lease shall require:

(a) Diligent development; and

(b) Either (1) continued operation except when operations under the lease are interrupted by strikes, the elements or casualties not attributable to the lessee, or (2) in lieu thereof, when the Secretary determines that the public interest will be served, payment of an advanced royalty.

[47 FR 33151, July 30, 1982, as amended at 50 FR 8627, Mar. 4, 1985]