The group included members of the Missourians Organized for Reform and Empowerment (MORE) as well as Navajo residents from Black Mesa, Arizona and a group of Appalachians from West Virginia.

According to local newspaper the Post-Dispatch, the demonstrators attempted to deliver a letter and speak to Peabody chief executive officer Greg Boyce. However, their plan was thwarted when they were blocked by police.

Nine men and three women were ultimately arrested, the paper said, after they crossed a barrier and refused to leave.

MORE official Zack Chasnoff said the group wanted Peabody “to at least have a dialogue with the indigenous people” of Black Mesa Indigenous Support about the surface complex near the north-eastern Arizona reservation.

About 50 demonstrators walked outside of Peabody headquarters to “raise awareness” of their plight as well as their opposition to coal pollution and climate change.

Peabody spokesman Vic Svec said the issue brought by the protesters with an “anti-everything agenda” were loose with the facts.

“Peabody’s Arizona operations are recognized globally for sustainable mining practices in the areas of safety, training, the environment and social responsibility,” he said.

He also noted that the producer reclaims mine land to a condition that was “as much as 10 times as productive as native lands” and said mining operations provide more than $US100 million each year to the economy of the reservation.

No information was available on the detained demonstrators’ charges or bail amounts.

On Tuesday, Arch Coal confirmed that seven protestors from two environmental groups gathered inside its Missouri headquarters and chained themselves together in alleged anger over the company’s business practices.

Members of MORE and Mountain Justice wrapped the chain around a 500lb potted tree on the third floor of the building outside of the building’s entrance.

The group told media that its primary complaint was strip mining practices by Arch and another coal company in West Virginia.

Arch spokeswoman Kim Link told ILN that some of the demonstrators were arrested.

“Coal creates affordable energy around the world and thousands of jobs here in the US,” she said.

“Arch is committed to providing responsible energy that powers the working world and meets the stringent environmental standards of US regulators.”