NEW DELHI: State Bank of India, cash-strapped Kingfisher Airlines ' largest creditor, has called the Vijay Mallya-led air carrier a non-performing asset."Kingfisher is a NPA (non-performing asset) for us. They are in default," SBI Chairman Pratip Chaudhuri told reporters here on Thursday.SBI, the leader of the consortium of banks that have lent funds to Kingfisher Airlines, has an exposure of Rs 1,457.78 crore to the struggling firm. SBI's exposure is the highest among any of the lenders to the airline, followed by IDBI Bank (Rs 727.63 crore), Punjab National Bank (Rs 710.33 crore), Bank of India (Rs 575.27 crore) and Bank of Baroda (Rs 537.51 crore).The private carrier is in a financial mess and struggling to service its loans, which have run up to over Rs 6,000 crore.Kingfisher reported a net loss of Rs 469 crore for the July-September quarter of the current fiscal, though its revenues rose by 10.2 per cent to Rs 1,528 crore. In the last fiscal ended March 31, 2011, it posted a loss of more than Rs 1,000 crore.Late last year, Kingfisher announced various business rationalisation initiatives, including phasing out of its low-cost Kingfisher Red service and reconfiguration of its fleet.The airline has been under pressure from its huge debt liability, besides increased expenses associated with fuel costs and operations, and had restructured its loans last year to lower costs.It is also said to be in talks with banks and some potential investors for fresh funds.