New Delhi, Aug 22 (IANS) State-owned oil marketing firms on Thursday evening stopped fuel supply to national carrier Air India over non-payment of dues at six airports.The OMCs led by the IndianOil has stopped jet fuel supply at six airports -- Ranchi, Mohali, Patna, Vizag, Pune and Cochin. According to an airline official, discussions are underway to resolve the matter with OMCs and that Air India has already paid Rs 60 crore as lump sum. --IANS nk-rv/pgh/