(teleSUR) Local police officers used tear gas as hundreds of protesters tried to halt the construction of the Dakota Access pipeline at Standing Rock.

More than 80 protesters were arrested Saturday after clashing with police in a demonstration against the Dakota Access pipeline construction site in North Dakota, the local sheriff’s department said and admitted to using tear gas against the protest where hundreds of Native American nations have been gathering for months to demand the project’s cancellation.

The 83 protesters were arrested on numerous charges ranging from assault on a peace officer to rioting and criminal trespass, the Morton County Sheriff’s department said in a statement.

Meanwhile, on Sunday, reports on social media also said that more than 800 protesters from various tribes blocked the main highway at Standing Rock, which would amount to almost the entire encampment.

The protesters used cars and their own bodies to block the highway. Police reportedly made arrests despite the peaceful nature of the action.

On Saturday morning, police responded to a report about an SUV on private property near the pipeline construction site and found that four men had attached themselves to the vehicle. Police removed the men from the SUV before arresting them.

Kellie Berns, a protester who hung back behind a fence at the scene, told the local Bismarck Tribune people were being pepper-sprayed and thrown to the ground and added that law enforcement was more aggressive than in past confrontations.

“People came back very distressed,” she said of those who returned to the fence following the demonstration. “The pipeline is getting a lot closer, so the stakes are getting higher.”

The demonstration closed a section of a local highway, but it was reopened on Saturday afternoon.

“This protest was intentionally coordinated and planned by agitators with the specific intent to engage in illegal activities,” sheriff Kyle Kirchmeier said in a statement, defending the use of force in removing and arresting the protesters.

The Standing Rock Sioux tribe and environmental activists have been protesting construction of the 1,100-mile pipeline in North Dakota for several months, saying it threatens the water supply and sacred sites.

The action against the pipeline has attracted more than 300 Native American tribes from across the United States as their cause secures national and international support.

Last month Dave Archambault II, chairman of the Standing Rock Sioux nation, spoke at the United Nations in Geneva, calling on the U.N.’s Human Rights Council to intervene to stop the construction of the pipeline while complaining that U.S. courts had failed his people.

More than 1,200 archaeologists, anthropologists, curators, museum officials and academics signed a letter in support of the protests against the Dakota Access pipeline and calling on the U.S. government and its agencies to put an end to the construction of the oil facility.

This post originally ran on teleSUR.