The North Dakota state court has found Greenpeace liable for nearly $667m in damages following its participation in 2016–17 protests against the Dakota Access pipeline, which is situated near the Standing Rock Indian Reservation.

Energy Transfer, a Texas-based pipeline company, accused Greenpeace of unlawfully disrupting the construction and disseminating false information about the project, as reported by Reuters.

After two days of deliberations, the jury concluded that the environmental advocacy group was responsible for defamation, trespassing and conspiracy during the protests.

The jury’s verdict included more than $400m in punitive damages, intended to penalise the defendants for their actions.

Despite the ruling, Greenpeace denied any wrongdoing, calling the case an attack on free speech rights. The group’s lawyers announced plans to appeal the verdict.

Greenpeace attorney Deepa Padmanabha said: “We are an advocacy group. We engage in peaceful protest.”

Meanwhile, Energy Transfer lawyer Trey Cox stated that Greenpeace’s “violent and destructive” protests were not legally protected speech.

Cox said: “Today, the jury delivered a resounding verdict, declaring Greenpeace’s actions wrong, unlawful and unacceptable by societal standards. It is a day of reckoning and accountability for Greenpeace.”

The Dakota Access pipeline project started in 2016 and was completed in 2017. The pipeline carries around 40% of the oil produced in North Dakota’s Bakken region.

Energy Transfer said the verdict was a “win for all law-abiding Americans who understand the difference between the right to free speech and breaking the law”.

“While we are pleased that Greenpeace has been held accountable for their actions against us, this win is really for the people of Mandan and throughout North Dakota who had to live through the daily harassment and disruptions caused by the protesters who were funded and trained by Greenpeace,” the company said in a statement to USA Today.