Mahanagar Telephone Nigam Limited (MTNL) may soon be declared a 'Non-Performing Asset' (NPA) by its lenders after having defaulted on its loan repayments for past few months, a report said. Union Bank of India and Bank of India have already classified MTNL's debt as NPA, and other banks, including SBI, UCO Bank and PNB are likely to follow, report added.