N Dakota pipeline protesters

Riot police move in on N Dakota pipeline protesters

"Non-lethal" shotgun bean bag rounds and pepper spray were being used to subdue protesters at a North Dakota camp, the Associated Press quoted a state official as saying.

Two helicopters and a fixed-wing aeroplane flew overhead as officials made warnings over a loudspeaker.

The $3.7bn (£2.8bn) Dakota Access pipeline has prompted huge protests.

Native Americans have halted its construction in North Dakota. The pipeline will run 1,168 miles (1,870km) through Iowa, Illinois, and North and South Dakota.