Housing loans disbursed by Indian banks surged by 15.6% in the past 12 months to Rs 10.5 lakh crore, but one-third of this amount given to economically weak borrowers is giving bankers sleepless nights.

According to analysis of data released by the Reserve Bank of India (RBI), banks’ home loan exposure grew by Rs 1.42 lakh crore, second only to the jump in lending to Non-Banking Financial Companies (NBFCs).

The NBFC sector, which has been reeling under stress recently due to defaults by financial services firm IL&FS, notched up a Rs 1.6 lakh crore growth in credit. But overall loans to the housing sector are almost double the lending to NBFCs.

According to real estate firms, the uptick in loan growth to the sector is driven by the affordable housing segment.

“People who buy luxury apartments don’t need housing loans…anyway, the luxury apartments segment is not doing so well,” said a top Bengaluru-based real estate executive who asked not to be named.

According to data provided by real estate advisory Anarock, the number of homes sold in the affordable housing segment has seen a jump of 32.5% over the same period last year. Affordable housing accounted for about 40% of all supply in seven major cities from January to October this year.

According to RBI’s research, housing loans up to Rs 2 lakh had the highest level of non-performing assets (NPAs) or bad loans, essentially loans on which defaults are likely, in 2016-17.

The apex bank said in a report earlier this year that NPAs in the sub-Rs 2 lakh ticket size were the highest at 10.4% for the period under consideration.