Vietnam blogger Pham Minh Hoang deported to France
Pham Minh Hoang served a jail sentence after being convicted in 2011 over articles that "blackened the image of the country".
Hoang, 62, was arrested in Ho Chi Minh City on Friday after losing his appeal against deportation.
It is rare for dual-nationals to lose the nationality of their country of origin.
US-based Human Rights Watch called the move "unprecedented and shocking".
After arriving in Paris on Sunday, Hoang described how Vietnamese police had surrounded his house and taken him away with no prior warning.
He was allowed to meet French consular officials but could not say goodbye to his wife, Le Thi Kieu Oanh.
"It's Hoang's ideal to stay in Vietnam to raise a voice and contribute to building freedom and democracy," Oanh told Reuters news agency.
In a statement, the French embassy in Ho Chi Minh reminded Vietnam of human rights agreements on the freedom of expression it was a party to and must observe.
Human Rights Watch said the Vietnamese action "crosses many human rights red lines on freedom of expression, right to nationality and exercise of basic civil and political freedoms".
Human rights activists say dozens of government critics in Vietnam have been given long jail terms in recent years.