The Oceti Sakowin camp is seen during a protest against plans to pass the Dakota Access pipeline. (Stephanie Keith/Reuters)

Activists protesting plans to run an oil pipeline beneath a lake near the Standing Rock Sioux reservation in North Dakota said Saturday that they have no intention of leaving a protest camp after U.S. authorities said it must be vacated by Dec. 5.

The U.S. Army Corps of Engineers, which manages the federal land where the main camp protesting the Dakota Access pipeline is located, said it would close public access to the area north of the Cannonball River, including to protesters. It said this was partly to protect the public from violent confrontations between protesters and law enforcement that have occurred in the area.

Those who stay could face prosecution for trespassing, the corps said in a letter to tribal leaders Friday.

Organizers said at a news conference Saturday at the main protest site, where about 5,000 people have camped, that they had no intention of moving.

“We are staying here, committed to our prayer,” said Dallas Goldtooth, an organizer with the Indigenous Environmental Network. “Forced removal and state oppression? This is nothing new to us as native people.”

There are smaller camps on land not subject to the planned restrictions, including an area south of the Cannonball River where the Army Corps said it was establishing a free-speech zone.

North Dakota Gov. Jack Dalrymple (R) on Saturday said that he supported the decision and that the federal government, which he said had allowed the protesters to become entrenched, must lead in the camp’s peaceful closure.

Standing Rock Chairman Dave Archambault said he received notice Friday about the decision in a letter from Col. John Henderson, an Army Corps district commander. Archambault said the best thing the federal government could do for safety is to deny the easement for the pipeline. “We have an escalating situation where safety is a concern for everybody,” Archambault said.

Demonstrators have protested for months against the $3.8 billion Dakota Access Pipeline, owned by Energy Transfer Partners, saying it poses a threat to water resources and sacred Native American sites. The company says the pipeline would carry Bakken shale oil more cheaply and safely from North Dakota to Illinois en route to U.S. Gulf Coast refineries.

The 1,172-mile project is mostly complete except for the segment planned to run under Lake Oahe, less than half a mile north of Standing Rock.

— Reuters