Police have sealed off a patch of University of California, Berkeley land that has been occupied by protesters for nearly three weeks.
The university police went to the property in Albany around noon Thursday and announced it was closed to pedestrian traffic.
Officers were allowing people to leave, but no one has been allowed to enter the 10-acre site.
The move by police comes after officers on Wednesday put barricades around the property to keep vehicles from coming and going.
The university also filed a lawsuit against the protesters on Wednesday, saying they had established an illegal encampment.
The protesters, on the property since April 22, have pitched tents and planted crops to protest planned housing and commercial development nearby.
University officials claim protesters are disrupting agricultural research by faculty scientists and students.
A university spokesman said the land is an open air laboratory where researchers work on agricultural projects.
In a statement released by the university, the school said: “It is our intention to facilitate a win-win situation whereby the land can be shared by our researchers and those who wish to sustain urban farming on the property.”
Supporters of Occupy the Farm told KTVU they planned to spend the night at the Gill Tract land in support of those inside the gates. And they brought them supplies Thursday evening.
“Bit by bit, over the last 100 years, it's been sold off and developed,” said Effie Rawlings, an Occupy the Farm protester.
Occupy the Farm protesters maintain they took over the land to preserve it for public good.
Watchdogs are questioning an exclusive agreement between the City of Oakland and a non-profit group, tapped to lead a multi-million dollar project to redevelop the area around the Coliseum BART station.