(CNN) Six human rights activists in Vietnam have been sentenced to between seven and 15 years in jail, in a move condemned by the US as part of a "disturbing trend" by the country's authorities to restrict fundamental freedoms.

The state-run Vietnam News Agency said Thursday the Hanoi People's Court had given the longest sentence to human rights lawyer Nguyen Van Dai, for "trying to overthrow the people's administration."

The judgment comes amid a wider government crackdown on peaceful dissent that has seen several bloggers and human rights activists given long jail sentences in the last 12 months.

"Individuals have the right to the fundamental freedoms of expression, association, and peaceful assembly, both online and offline," said US State Department spokesperson Heather Nauert in the statement

"The United States is deeply concerned by the Vietnamese government's efforts to restrict these rights, through a disturbing trend of increased arrests, convictions, and harsh sentences of peaceful activists."

Protesters display placards as they march towards a courthouse during the trial of a prominent lawyer and five other activists in Hanoi on April 5.

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