We investigate the origin of a long-lived earthquake cluster in the Fars arc of the Zagros Simply Folded Belt that is co-located with the major Shanul natural gas field near the small settlement of Khalili. The cluster emerged in January 2019 and initially comprised small events of w 5.4 and 5.7 earthquakes, which were followed by > 100 aftershocks. We assess the spatio-temporal evolution of the earthquake sequence using multiple event hypocenter relocations, waveform inversions, and Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) measurements and models. We find that the early part of the sequence is spatially distinct from the June 9, 2020 earthquakes and their aftershocks. Moment tensors, centroid depths, and source parameter uncertainties of fifteen of the largest (Mn ≥ 4.0) events show that the sequence is dominated by reverse faulting at shallow depths (mostly ≤ 4 km) within the sedimentary cover. InSAR modelling shows that the Mw 5.7 mainshock occurred at depths of 2–8 km, with a rupture length and maximum slip of ~20 km and ~0.5 m, respectively. Our results strongly suggest that the 2019-2020 Khalili earthquake sequence was influenced by the operation of the Shanul field, making these the first known examples of gas extraction anthropogenic earthquakes in Zagros. Understanding the genesis of such events to distinguish man-made seismicity from natural earthquakes is helpful for hazard and risk assessment, notably in Iran which is both seismically-active and rich in oil and gas reserves.