President Barack Obama has said army engineers are looking into whether the controversial oil pipeline in North Dakota could be rerouted after months of protests.

Mr Obama said in an interview that he would let the conflict to play out for "several more weeks" to see if the issue could be resolved.

The Dakota Access pipeline threatens a Native American reservation.

Activists clashed with police in riot gear and armed with pepper spray on Wednesday.

“My view is that there is a way for us to accommodate sacred lands of native Americans,” Mr Obama told NowThisNews, “and I think that right now the Army Corps is examining whether there are ways to re-route this pipeline.”

A federal judge ruled the pipeline work could go forward, but the US Army Corps and two other agencies said work would not be continued in an area that was particularly sensitive to the tribe until after a review was completed.

The pipeline has been rerouted 50 feet so far after the development company dug up native artefacts. The company faces heavy fines from regulators as it did not report the findings for 10 days.

Mr Obama said the protests presented a “challenging situation” and compared it to the Black Lives Matter movement.

Earlier that day protesters had been treated for hypothermia after trying to wade across the Cannonball river to access land owned by the pipeline developer. Protesters tried to build a wooden bridge across the river, but it was taken down by Morton County officials.

“There is an obligation for protesters to be peaceful, and there's an obligation for authorities to show restraint,” he said.

Hollywood Stars Join Standing Rock Sioux Members to Protest North Dakota Pipeline

“I want to make sure that as everybody is exercising their constitutional rights to be heard, that both sides are refraining from situations that might result in people being hurt.”

Chairman of the Standing Rock Sioux, Dave Archambault II, said, “We believe President Obama and his administration will do the right thing.”

Police have arrested nearly 150 activists so far.

The first protests were led by Native Americans of the Standing Rock Sioux, who fear the $3.7 billion pipeline could pollute their drinking water and damage their reservation.

More than 1.4 million people have “checked in” to the protest location on Facebook in solidarity and to confuse police.

Vicki Granado, spokeswoman for the pipeline company, Energy Transfer Partners, said in a statement, “We are not aware that any consideration is being given to a reroute, and we remain confident we will receive our easement in a timely fashion.”