Former chairman and founder of Dai Duong (Ocean) Bank, Ha Van Tham, has been announced today by police to be held for four months for investigating his financial irregularities.

He was charged by police of violating regulations on granting loans as ruled at the Article 179 of the Criminal Law.

Hours before the arrest, the State Bank of Vietnam announced to suspend his post as the chairman of the executive board of the bank.

Nguyen Minh Thu, member of the board of directors of Ocean Bank, was elected to replace the chairmanship.

The firm has a chartered capital of VND3 trillion (US$141.6 million) and has interests in real estate, banking, securities, retail, media and hotels, according to Reuters.

Ocean Group shares have fallen as much as 15 percent since Wednesday on Vietnam's main stock market, which traders said was in response to market rumors of Tham's arrest.

Volume of trading in the stock hit a record high of 22.4 million shares on Thursday, or 15 percent of total volume. Ocean Group closed Friday down 2.68 percent, at 10,900 dong a share, but off an earlier low of 10,500.