Two other bloggers -- also members of the Free Journalists Club -- Ta Phong Tan, 44, and Phan Thanh Hai, 43, were sentenced to 10 years and three years in prison by the Ho Chi Minh City People's Court, VNExpress reported.
The U.S. Embassy in Hanoi expressed its concern over reports that the court convicted and sentenced the 60-year-old Dieu Cay "for peacefully expressing his political views."
"The government's treatment of Dieu Cay appears to be inconsistent with Vietnam's obligations under the International Covenant on Civil and Political Rights, as well as the provisions of the Universal Declaration of Human Rights relating to freedom of expression and due process," the embassy said.
The embassy urged the Vietnam government to release the three bloggers.
VNExpress said the three are thought to have posted more than 400 articles on a blog, including 26 items containing anti-state comments.