A Vietnamese court has sentenced 22 members of an outlawed Buddhist sect to lengthy prison terms for attempting to overthrow the Communist government, in one of the largest such trials in years.

Lawyer Nguyen Huong Que says the group leader Phan Van Thu was sentenced to life in prison while 21 others, including his son, were given jail terms ranging from 10 to 17 years behind bars by the People's Court in central province of Phu Yen at the end of the week-long trial Monday.

Que said the group, which operated under the cover of an ecotourism company, authored documents vilifying the government.

The government appears to be stepping up its campaign against dissidents despite criticism from Western governments. Last month, 14 activists were sentenced to up to 13 years.