North Dakota’s governor has ordered the expulsion of thousands of Native American and solidarity activists camped on government property near an oil pipeline project they are trying to stop, citing hazards posed by harsh winter weather as a blizzard bore down on the area.

The “emergency evacuation” order from Governor Jack Dalrymple came days after the US Army Corps of Engineers, which manages the site, said it would give the demonstrators until December 5 to vacate their encampment, about 45 miles (72 km) south of Bismarck, the state capital.

Over the weekend, the US Army Corps of Engineers said in a statement that it was “seeking a peaceful and orderly transition to a safer location”, but had “no plans for forcible removal” of protesters.

Dalrymple’s evacuation order came a week after local law enforcement sought to disperse the demonstrators, many of them members of the Standing Rock Sioux Tribe, by spraying them with water in sub-freezing temperatures.

A spokeswoman for the tribe, whose reservation lies about half a mile (0.8km) from the proposed route of the Dakota Access Pipeline, did not have an immediate comment.

But activists who have spent months protesting against plans to route the oil pipeline beneath a lake near the Standing Rock reservation have vowed to continue their resistance to a project they say poses a threat to water resources and sacred Native American sites.

READ MORE: Life on the Pine Ridge Native American reservation

The governor cited the protesters’ own wellbeing in ordering a mandatory evacuation, though he did not specify how he intended to enforce the measure, other than by directing state and local agencies to refuse emergency assistance and other services to those who remained at the site.

He said the order was effective immediately and would remain in force “until rescinded”.

“Winter conditions have the potential to endanger human life, especially when they are exposed to these conditions without proper shelter, dwellings or sanitation for prolonged periods of time,” the order said.

It added that the area, just north of the Cannonball River, was “not zoned for dwellings suitable for living in winter conditions.”

‘Forced removal is terrifying’

Many protest leaders rejected the order, arguing that a forced removal would put the activists in greater danger.

“We’re in the heart of winter now. To even think of a forced removal is terrifying,” said Dallas Goldtooth, an organiser with Indigenous Environmental Network, who estimated there were around 5,000 people in the camp.

North Dakota’s governor has claimed the wintry conditions will put the protesters’ lives at risk [Stephanie Keith/Reuters]

“They don’t need to be worried about us in the winter,” said Kandi Mossett, also a member of the network. “We’re perfectly capable of being self-sufficient. So, using this as an excuse is insulting.”

Morton County Sheriff Kyle Kirchmeier added to the pressure on Monday by issuing a video statement urging protesters to avoid subjecting themselves to “life-threatening conditions” by remaining exposed to the elements with little shelter.

READ MORE: Dakota pipeline – ‘It’s our right to live unharmed’

The National Weather Service has posted a winter storm warning for most of western and central North Dakota, forecasting the possibility of heavy snow through Wednesday.

The $3.8bn, 1,172-mile (1,885km) pipeline project is complete, except for a segment that is supposed to run under Lake Oahe, a reservoir formed by a dam on the Missouri River.

The Obama administration in September postponed final approval of an Army Corps permit required to allow tunnelling beneath the lake, a move intended to give federal officials more time to consult with tribal leaders. The delay also led to escalating tensions over the project.

The companies say the pipeline would carry Bakken shale oil more cheaply and safely from North Dakota to Illinois en route to US Gulf Coast refineries than it could be shipped by railroad or tanker trucks.

More than 5.1 million people in the US identify as fully or partially Native American or Alaska Native, according to the US Census Bureau. Up to 2.5 million identify as fully indigenous Native American or Alaska Native.

The International Work Group for Indigenous Affairs, a human rights organisation, said the US government had a lengthy history of “criminalis[ing] indigenous rights defenders’ struggle for respect”.

“We strongly appeal to the US government to immediately cease the use of violence against those protesting at the Dakota Access Pipeline, refrain from militarisation and other forcible actions against the Native American protesters,” the group said in a statement.