A U.S. group advocating for the rights of women said the federal government should intervene in Dakota oil pipeline protests in order to halt the violence.

More than a hundred demonstrators have been arrested during ongoing protests over the construction of a 1,100-mile pipeline meant to carry oil from North Dakota to refineries along the southern U.S. coast. The Standing Rock Sioux tribe and its supporters have tried to block the construction through the courts and through protests, saying the pipeline would threaten tribal sites and regional water supplies.

The Women Donors Network said in an emailed statement the reaction from law enforcement officials in North Dakota took a turn for the worse and it was now time for the U.S. Justice Department to intervene.

"From dog attacks, to local women being stripped naked and left that way in jail overnight, to arrests used as a tool for intimidation -- these reports are very disturbing," WDN President Donna P. Hall said. "The DOJ must act immediately to investigate local North Dakota police and hold them accountable for any abuses of power."

According to reports, some activists were attacked by dogs used by security personnel attempting to control the protests. North Dakota authorities are investigating possible license violations related to those incidents.

Sheriffs in North Dakota from Morton County called for additional personnel from neighboring states to assist with law enforcement efforts. Morton County Sheriff Kyle Kirchmeier said in a statement much of the protest activity was illegal, citing incidents ranging from trespassing to firing arrows in the direction of security officers.

The companies behind the Dakota Access pipeline said the infrastructure is needed to accommodate and distribute the amount of crude oil being produced from the Bakken shale oil basin in North Dakota. Because of insufficient pipeline capacity in the region, railcars are used to make up the shortage, a transport method for oil that has its own public safety risks. At least 40 people were killed in Lac-Megantic, Quebec, in the 2013 derailment of a train carrying tankers of crude oil from the state to Canadian refineries.