Today´s official Quan Doi Nhan Dan (People´s Army) newspaper said Father Nguyen Van Ly had been put under "administrative detention" in the central province of Thua Thien Hue, the news service said.
Father Ly, 54, has spent more than a decade in jail or detention since the communist victory in the Vietnam war in 1975 for his criticisms of government religious policies.
Last month, in testimony prepared for a hearing in Washington of the U.S. Commission on International Religious Freedom, Father Ly urged a halt to the trade pact, saying Washington should not to give support to Vietnam´s communists to "prolong their totalitarian dictatorship."
The trade pact was signed last July after years of haggling and will give Vietnam access to the massive U.S. market. But it has still to be approved by the U.S. Congress and Vietnam´s National Assembly. Ratification is vital if Vietnam is to achieve its aim of boosting its export industries and levels of foreign investment, which have slumped since peaks in the mid-1990s.
Analysts say recent human rights issues that have cropped up will make for a rough ride in Congress and Father Ly´s detention will only make matters worse.