The watchdog is investigating whether Paul Watson, head of regulatory compliance at the unit, possesses the competency to carry out the role, according to two people familiar with the matter.
The fresh regulatory investigation comes as the Asia-focused bank tries to return to growth following the end of a five-year period during which it was threatened with criminal charges in the US for its role in money-laundering and sanctions-breaking.
Mr Watson, who has worked at the bank for 15 years according to his LinkedIn profile, has not been suspended and is still discharging his duties, one of the people said.
The person said there was no suggestion Mr Watson had been involved in misconduct or suspicious activity, but the probe pertained to whether he was competent at his job. Sky News first reported the matter.