Claim of gst after completion of contract period

reena (A) (26 Points)

22 June 2023  
hi,
the contractor was alloted with supply of manpower in our organizations.. though he was registered under gst act.. he never raised gst invoice n claimed.. after completion of contract period he receivied notice from gst department ..he remitted gst with penalty..now he is claiming for reimbursement of gst amount paid by him from our organization.. do we have any obligation to reimburse him the gst amount? or we can reject him claim since it is supplier responsibility to raise tax invoice n claim gst?