Those arrested by anti-corruption police late Tuesday include former chairman Hoang Van Toan and CEO Tran Son Nam of TrustBank, the state-run Tuoi Tre newspaper said.
Under their management the bank approved two loans that "caused a loss of 21 million dollars to TrustBank", the report said.
After their tenure ended, the bank changed its name to Vietnam Construction Bank in 2013 and became engulfed in an even greater corruption scandal that reportedly caused a record USD 400 million in losses.
Communist Vietnam has one of the strongest-performing economies in the region, clocking in 6.2 percent GDP growth last year.
But high public debts, bloated state-owned enterprises and rampant official corruption have made economic progress vulnerable.
The banking sector in particular has been rocked by a series of scandals in recent years, with high-profile arrests of wealthy businessmen and executives accused of corruption, embezzlement or incompetence.