Dinh Nhat Uy, 30, was found guilty under Article 258 of the penal code, Huy Ha Son said.
“It is not house arrest but he has to report his movements to the local police,” Son said.
The case attracted attention in Vietnam’s blogosphere for being the first to focus on the popular social media network.
“I would argue that this is one of the first cases in Vietnam where Facebook has been central to what he’s being charged with,” said Phil Robertson, deputy Asia director at Human Rights Watch.
Uy posted pleas for the release of his brother, 26-year-old Dich Nguyen Kha, who was sentenced in May to eight years in prison for distributing leaflets criticizing “the party and the state’s policies related to religion and land,” and its policies on border disputes with China, state media reported.
His sentence was later reduced to four years.
Vietnam has come under criticism for an increasing crackdown on government critics. So far in 2013, 61 activists have been taken to court compared to around 40 in 2012, according to Human Rights Watch.
Nguyen Tri Dung, the son of jailed blogger Nguyen Van Hai, told dpa that Uy’s trial has not discouraged him from using Facebook to call for the release of his father.
“I am not worried, I’m prepared for that because I know they can catch me any time,” he said.