The US Army Corps of Engineers has denied an easement for the hugely controversial Dakota Access Pipeline, according to the Standing Rock Sioux tribe.

Thousands of people - including the Sioux - have been protesting plans to pass the $3.8 billion Dakota Access pipeline near the Standing Rock Indian Reservation, near Cannon Ball in North Dakota.

The 1,172-mile (1,885km) pipeline, owned by Texas-based Energy Transfer Partners, is mostly complete aside from a segment planned to run under Lake Oahe, a reservoir formed by a dam on the Missouri River.

The disputed land is managed by the Corps, and more than 3,000 veterans had joined the protesters on the ground.

In a statement, the tribe said the Corps had denied the easement which would have allowed the pipeline to cross the lake.

"Instead, the Corps will be undertaking an environmental impact statement to look at possible alternative routes," they added.

The Sioux tribe have been joined by climate activists in protesting the proposals, saying it could contaminate the water supply.