Bloggers attending an anti-China protest in Hanoi (Reuters)
Bloggers attending an anti-China protest in Hanoi (Reuters)

Vietnamese authorities have sentenced 14 pro-democracy activists to harsh sentences on charges of attempting to overthrow the communist government in a fresh crackdown on dissent.

Three of the defendants, arrested in 2011 on suspicion of connections to the banned opposition group Viet Tan, were jailed for 13 years each, according to several blogs. The People's Court in Nghe An province sentenced the others to terms of between three and eight years.

Based in the US, Viet Tan is considered a terrorist organisation by the Vietnamese government.

The 13, including bloggers and members of the Catholic Church, were found guilty of "carrying out activities aimed at overthrowing the people's administration" under Article 79 of the penal code.

Human rights group criticised the sentence and said that the article was "draconian".

"There is nothing to indicate that the defendants intended to overthrow the government," said Phil Robertson, deputy Asia director at New York-based Human Rights Watch.

"This trial is in the middle of a deepening crackdown that's been gradually picking up speed in the past year and a half. They're mowing down the ranks of activists in Vietnam," he said.

The US embassy in Hanoi said it was "deeply troubled" by the reports.

"The government's treatment of these individuals 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," it said.

Viet Tan Duy Hoang said: "By persecuting these individuals for their peaceful expression and political advocacy, the Hanoi regime has shown once again its fear of civil society.

"Viet Tan stands in solidarity with these 14 human rights defenders and will continues to advocate for [their] unconditional release from arbitrary detention."

The sentences came after a Vietnamese blogger claimed she was sexually assaulted by police officials after being taken into custody on suspicion of hiding "illegal exhibits" about her body.