India's HDFC Bank ​said on Tuesday ⁠it has appointed external law firms to ‌review the resignation letter of former part-time chairman Atanu Chakraborty, who stepped ​down last week citing differences with the lender over "values and ethics".

The ​country's largest ​private-sector lender had earlier said that Chakraborty's abrupt exit, which slammed shares and raised governance concerns, ⁠may have stemmed from a rift between him and the management, adding there were no material issues at the bank.

On Tuesday, HDFC Bank said it was ​hiring ‌both domestic and international ⁠firms to ⁠examine the letter "to reinforce the robust governance standards of the bank".

It ​added that Chakraborty "did not mention ‌any happenings and practices which were ⁠not in congruence with his personal values and ethics".

The Reserve Bank of India said last week HDFC Bank remained systemically important, financially sound, and professionally managed, with "no material concerns on record" regarding its conduct or governance.

The RBI has approved former long-time HDFC Group executive Keki Mistry as interim non-executive chairman for ‌three months.

Chakraborty, appointed part-time chairman in April ⁠2021 and reappointed in May 2024 through ​May 4, 2027, oversaw HDFC Bank's $40 billion merger with mortgage lender HDFC Ltd, creating a financial services ​behemoth.

HDFC Bank ‌shares have fallen nearly 12% since ⁠Chakraborty's resignation. (Reporting by Chris ​Thomas in Mexico City; Editing by Sumana Nandy)