BANGKOK — A court in central Vietnam convicted 14 bloggers, writers and political and social activists on Wednesday of plotting to overthrow the government and sentenced them to prison terms ranging from 3 to 13 years in what human rights groups said was the largest subversion case to be brought in years.

The defendants were arrested in 2011 and accused of links to a banned pro-democracy group led from California. The government says the group — Viet Tan, or Vietnam Reform Party — seeks its overthrow.

A number of the defendants are members of the Redemptorist group in the Roman Catholic Church, which has been engaged in community service and has taken up the causes of land seizures and corruption. Redemptorist activists have become increasingly assertive in Vietnamese movements for democracy and human rights, and some churches and parishes have become centers of dissent.

Nguyen Thi Hue, a defense lawyer, told The Associated Press in Vietnam that three defendants in the two-day trial in the city of Vinh, in Nghe An Province, had been sentenced to 13 years and that 11 others had received terms of three to eight years. One of the three-year terms was suspended.