the data on NPAs in banks in India for period before 1997 is available on RBI site--www.rbi.org. also see old publications and reports of RBI. You may make a request to Statistics and research division of RBI by stating clearly data is needed for academic not for commercial. IBA may also make the data available. Library of NIBM pune is very rich and one can get old literature and data about banks. One of my Ph. D student Dr.Richa Verma Bajaj, is a faculty at this institute, she may help you, on giving my reference.
Thanks Rajesh...I do checked the archives of RBI and they have reported Gross NPA's data starting from 1996-1997 only. In some of the papers, i find mention of npa increasing in 1990-1991 but no data as such..I have a time series data in which npa is one of my indepedent variable and this is restricting me to take data from 1996 which makes my no. of observations to 20 which is not good for a time series analysis. If i take quarterly data, then again i don't have npa quarterly data...Any help/idea !!