Do Duc Nam was accused of colluding with executives of two local companies, Louis Capital and Louis Land, to manipulate the companies' share prices by conducting "illegal" transactions, the ministry said in a statement.

The Southeast Asian country last month called for the crackdown to be stepped up, with a new target of cleansing the financial markets.

Tri Viet Securities said in a statement late on Wednesday that the arrest will not alter the company's future business direction, adding that it is cooperating with the investigators.

The police on Wednesday also arrested three other people for their involvement in the case, including executives of Louis Capital and Louis Land, the ministry said.

Late last month, Vietnam arrested the chairman of property and leisure company FLC Group and its Bamboo Airways subsidiary, on accusation of market manipulation.

A week later, police arrested Do Anh Dung, chairman of Tan Hoang Minh Group, another major property firm in Vietnam, on accusation of corporate bond frauds.

Other major arrests this month include that of a former commander of the Vietnam Coast Guard and a deputy foreign minister, on accusation of embezzlement and bribery.

(Reporting by Khanh Vu; Editing by Leslie Adler)