BILLINGS — The Blackfeet Tribe has taken the rare step of breaking off formal talks with the U.S. government and a Louisiana company that has been seeking for decades to drill for natural gas on land considered sacred by the Blackfeet people.

Blackfeet tribal leaders said that after three rounds of negotiations, they remain steadfast in their opposition to drilling in the Badger-Two Medicine area outside Glacier National Park and see no benefit to further discussions.

“We are not going to speak to anything other than no development,” Blackfeet Tribal Historic Preservation Officer John Murray said.

Solenex LLC of Baton Rouge acquired a 6,200-acre energy lease in the Badger-Two Medicine in 1982, but its attempts to develop the site have since been held up by federal officials. The company sued in 2013 to overturn a government suspension on the leases. It wants to begin drilling this summer.

That case is before U.S. District Judge Richard Leon, who has sharply criticized the government’s handling of the case and the long delay experienced by Solenex.

The head of the law firm representing Solenex said Thursday that the tribe’s end to the formal consultation process was yet another attempt to delay drilling.

“It’s something the tribe cannot stop,” said William Perry Pendley, president of the Mountain States Legal Foundation. “This land belongs to the U.S. government, the American people, and our client has a property right to it.”

The Badger-Two Medicine area is the home of the creation story of four tribes in Canada and Montana and the Sun Dance that is central to their religion. The land is part of the Lewis and Clark National Forest, but it is not on Montana’s Blackfeet Reservation.

Maria Zedeno is a professor of anthropology at the University of Arizona who has studied the area’s cultural significance for the tribe. She said drilling would disturb the Badger-Two Medicine’s sacred qualities much more than current uses such as people driving snow vehicles or all-terrain vehicles.

“What they have a problem with is disturbing the spiritual power that travels underground. Fossils are extremely sacred to the Blackfeet. They bring power to hunting, and they are in areas where they potentially can be disturbed by drilling,” Zedeno said.

Consultations between the tribe, government and the other parties in the dispute have taken place under a review process that’s guided by federal laws meant to preserve historic and cultural resources.

Nationwide there are some 110,000 such reviews annually, and on average only about once a year does a consulting party break off negotiations rather than work out an agreement, said Reid Nelson, director of federal agency programs at the Advisory Council On Historic Preservation.

The tribe’s end to consultations kicks of a 45-day deadline for the advisory council to issue recommendations to the Forest Service on how to proceed.

The council’s chairman likely will appoint a panel to look into the interests of all sides before coming up with recommendations, Nelson said. On Thursday, the council asked the Forest Service for a 30-day extension of the deadline due to the complexities of the case.

The Forest Service in December determined drilling would adversely affect the sacred site and reduce its spiritual power for the Blackfeet. The federal advisory council agreed with that finding in January.

Dozens of oil and gas leases were originally sold in the area, but over the years most have been retired or surrendered. Only 18 suspended leases remain, including Solenex’s.

Blackfoot leaders have asked Interior Secretary Sally Jewell to cancel the leases.

Fifteen of the leases are held by Oklahoma-based Devon Energy. The company’s general counsel and executive vice president, Lyndon Taylor, is listed as a board member of Solenex’s law firm, the Mountain States Legal Foundation.