About 20 people, some carrying knives, pressured the monks to leave, ripped their clothing from a line and tossed it into a nearby river, Tu said. A few days before that, the group smashed the windows of the meditation hall, he said.
Late Monday night, police searched the dormitory rooms of the nearly 400 monastery residents and took the identity cards of two monks, ordering them to attend a meeting with local government officials on Tuesday morning, Tu said.
Calls to the area's police chief and local officials went unanswered Tuesday.
The monks and nuns are followers of Thich Nhat Hanh, an exiled Vietnam-born monk who has sold more than 1 million English-books in the West and is now based at the Plum Village monastery in southern France. Nhat Hanh has visited Vietnam three times since 2005, but remains based in southern France at the Plum Village monastery and is currently not in Vietnam.
His followers say they are being punished because Nhat Hanh has suggested that Vietnam's communist government should abolish its control of religion.
Authorities describe the conflict as an internal dispute between two factions of monks. They say they are simply acting at the request of the monastery's owner, Duc Nghi, a member of the official Buddhist Church of Vietnam who invited Nhat Hanh's followers to settle at the pagoda in 2005 but changed his mind last year.
Nghi could not be reached for comment.
The tensions first boiled over last June, when a mob descended on the site with sledgehammers, damaged buildings and threatened the monks and nuns who follow Nhat Hanh. Authorities also cut off electricity at the site.
Authorities later decided to allow the monks to stay until Sept. 2, but they declined to leave, saying they have no place to go and have spent nearly $1 million expanding the property and adding buildings.
The deadline passed without incident.