A court in Hanoi rejected an appeal by a prominent Vietnamese blogger on Thursday and upheld his five-year prison sentence for anti-state writings.

Nguyen Huu Vinh, better known as Anh Ba Sam, was convicted of abusing democratic freedoms to infringe on the interests of the state at a one-day trial in March. His colleague, Nguyen Thi Minh Thuy, was given a three-year jail term on the same charge.

Presiding Judge Ngo Hong Phuc said 24 articles Vinh and Thuy posted on their two blogs sullied the prestige of the state and its leaders, and presented an incorrect understanding of the government's policies.

"The crimes committed by the defendants are serious, obviously infringing on the interests of the state," Phuc said. He said the lower court's sentences were "well-founded, in line with regulations of the law."

Vinh, 60, quit his former job as a policeman and set up a private investigation firm. He then launched the blog Dan Quyen, or Citizens' Rights, in 2013, and Chep Su Viet, or Writing Vietnamese History, in early 2014. The blogs provided links to news on political, social, economic and cultural issues from state media as well as from activists.

Prosecutors said the two blogs contained 2,397 articles and generated more than 3.7 million hits, and that 24 of the articles had "untruthful and groundless contents" which tarnished the country's image.

Vinh maintained his innocence throughout the trial.

"Once again I would like to declare that I'm absolutely innocent. I'm extremely proud of my contributions to society throughout the last nine years ... particularly the more than two years in prison. These are the finest, the most significant and happiest times of my life," Vinh said in his final words Thursday before the audio was cut off.

The defendants' lawyers said security police had violated the law when collecting evidence, and that it should not have been used against their clients.

Security around the court house near downtown Hanoi was tight, with roads blocked off.

Vinh's wife and son were allowed in the court, where six lawyers represented Vinh and Thuy. Diplomats and international media followed the proceedings in a separate room via closed circuit TV.

International human rights groups and Western governments including the United States have criticized Vietnam for jailing dissidents. Hanoi denies that, saying it only detains those who break the law.

New York-based Human Rights Watch called for the release of Vinh and Thuy.

"Vietnamese authorities have decided it is a crime to provide independent information to the Vietnamese public," Brad Adams, Asia director at Human Rights Watch, said in a statement Tuesday.

U.S. officials say Vietnam has made some progress in its human rights record with fewer arrests, but that more needs to be done if it wants to expand bilateral ties.