India, March 19 -- HDFC Bank on Wednesday said its chairman Atanu Chakraborty had resigned with immediate effect, with his March 17 letter to the board citing "certain happenings and practices within the bank" that were "not in congruence" with his personal values and ethics.

In a regulatory filing late Wednesday night, India's largest private sector lender said the Reserve Bank of India has approved the appointment of board member and HDFC group veteran Keki Mistry as interim part-time chairman for three months starting March 19.

The bank said Chakraborty submitted his resignation letter to the board on March 17. "We confirm that there are no reasons other than those mentioned in the said letter, for the resignation of Chakraborty," th...