North Dakota officials on Tuesday moved to block supplies from reaching oil pipeline protesters at a camp near the construction site, threatening to use hefty fines to keep demonstrators from receiving food, building materials and even portable bathrooms.

Activists have spent months protesting plans to route the $3.8bn Dakota Access Pipeline beneath a lake near the Standing Rock Sioux reservation, saying the project poses a threat to water resources and sacred Native American sites.

 North Dakota residents angered by pipeline protests

State officials said on Tuesday they would fine anyone bringing prohibited items into the main protest camp following Governor Jack Dalrymple's "emergency evacuation" order on Monday.

Earlier, officials had warned of a physical blockade, but the governor's office backed away from that.

Law enforcement would take a more "passive role" than enforcing a blockade, said Maxine Herr, a spokeswoman for the Morton County Sheriff's Department.

"The governor is more interested in public safety than setting up a road block and turning people away," Herr said by telephone.

A spokeswoman from the Standing Rock Sioux tribe was not immediately available for comment, and North Dakota Governor-elect Doug Burgum, a Republican, declined to comment.

The 1,885 km pipeline project, owned by Texas-based Energy Transfer Partners LP, is mostly complete, except for a segment planned to run under Lake Oahe, a reservoir formed by a dam on the Missouri River.

Thousands of people are protesting at camps located on U.S. Army Corps of Engineers land, north of the Cannonball River in Cannon Ball, North Dakota. The main protest camp near Cannon Ball is called Oceti Sakowin, the original name of the Sioux, meaning Seven Council Fires.

Snow storms and clashes

Dalrymple's evacuation order was issued on Monday due to the "harsh winter conditions." Snow and wind gusts up to 73 kph were forecast for Tuesday, according to the National Weather Service.

Despite the sub-freezing temperatures, law enforcement on November 21 used water cannon to disperse protesters who had blockaded a highway.

 North Dakota protesters blasted with water cannon in sub-freezing temperatures

Demonstrators and law enforcement have clashed over the months since protests began, with demonstrators claiming excessive use of force by law enforcement.

On Tuesday, the National Lawyers Guild filed a class action in US District Court in North Dakota on behalf of injured protesters, claiming local authorities in Morton and Stutsman counties used excessive force.

The civil rights complaint said there were no orders to disperse or warnings issued before local police turned water cannon and tear gas on the protest. The lawsuit seeks compensatory damages.

Stutsman County Auditor Casey Bradley said the county sheriff's office was unaware of the lawsuit and unable to comment on the allegations.

Officers were justified in using water cannon because of the threat posed by demonstrators, Herr said. Law enforcement gave numerous warnings for protesters to disperse, she said.

North Dakota officials have issued several requests for additional help from federal law enforcement in light of the demonstrators. However, the Corps said Monday its order to evacuate the primary protest camp by December 5 would not include forcibly removing people from the land.

The Obama administration in September postponed final approval of a Corps permit required to allow tunnelling beneath the lake, a move intended to give federal officials more time to consult tribal leaders.

Source: Agencies