By Kanga Kong 
 

SEOUL--South Korea's financial watchdog will investigate whether the local units of HSBC Holdings PLC (HBC) and Standard Chartered (SCZ.ZM) were involved in money laundering, the Financial Supervisory Service said Thursday.

"We will probe the Seoul branch of HSBC and Standard Chartered Bank Korea in relation to (alleged) money laundering at their U.S. and Mexico units," the FSS said in a statement. "We will look into various issues related to (potential) money laundering, including whether they reported suspicious transactions (to the authorities) and verified their customers (before carrying out transactions) as they're supposed to."

The news come at a time when the two U.K. banks are put under fire in the U.S., with HSBC accused by a Senate investigation of failing to prevent money-laundering at its Mexican subsidiary and Standard Chartered called out for allegedly helping Iranian banks to violate U.S. sanctions as well as misleading regulators.

Standard Chartered has denied the allegations made against it. HSBC has accepted some wrongdoing took place. HSBC Chief Executive Stuart Gulliver said last month the bank was working hard to improve its compliance systems.

A spokesman for HSBC's Seoul branch declined to comment. Standard Chartered Korea was not immediately available for comment.

Write to Kanga Kong at kanga.kong@dowjones.com