Pham Minh Hoang, 55, who trained in France, was arrested last Friday in southern Vietnam under Penal Code Article 79, his wife Le Thi Kieu Oanh told AFP.
People convicted under the article can be jailed or sentenced to death.
"I was really confused at that time, so I could not tell exactly what the reason for the arrest was," Oanh said.
Before Hoang's arrest, the couple had been questioned by police for two days and accused of being members of Viet Tan, the Vietnam Reform Party, she said.
Based in the United States, the group is banned in Vietnam and labelled a "terrorist group" by the one-party communist regime.
Oanh said she and her husband denied being members of Viet Tan.
He went to France in 1973 but returned after 27 years to settle in Vietnam, where he has been working as a mathematics lecturer at the Polytechnic University of Ho Chi Minh City, she said.
Police in the city refused to comment, and the Ministry of Foreign Affairs was not immediately able to make a statement.
msn.com
