Nguyen Ngoc Gia, arrested in 2014, was sentenced on Wednesday to four years in prison by a court in Ho Chi Minh City. He was accused of writing 22 articles defaming Communist Party leaders and the state, EFE news reported.
The three other activists were arrested during a protest against the expropriation of their land in front of the US consulate in Ho Chi Minh City.
They were also sentenced on Wednesday ranging from three to four years in prison for waving the former flag of South Vietnam in the protest.
The sentences were imposed a week after another blogger and his assistant were sentenced to five and three years in prison for publishing several articles criticising the government.
The Vietnamese government controls all media. In 2015, the country was ranked 175th out of 180 on the Press Freedom Index which was conducted by Reporters Without Borders, only ahead of China (176), Syria (177), Turkmenistan (178), North Korea (179) and Eritrea (180).(IANS)