An Indigenous roadblock has stopped workers and equipment heading to do preliminary work on a controversial open pit mine in the Chilcotin, west of Williams Lake, according to protesters.

But the company hoping to mine Canada's largest undeveloped copper-gold deposit said its work will continue.

"We have the legal authorization to go into those lands, provided by the provincial government," said Brian Battison, vice president of corporate affairs for Taseko Mines.

"They are the authority under the law. We have their approval under the law and we intend to act on it."

Members of the Tsilhqot'in Nation said they camped out overnight Monday in rugged ranch land near Riske Creek, an hour's drive from Williams Lake.

They said they blocked a back road Tuesday morning — used to access Taseko's proposed New Prosperity Mine — with their pickup trucks. Men in high visibility vests stood on Highway 20 to stop trucks hauling heavy equipment.

The Tsilhqot'in protesters say they turned back two trucks carrying equipment bound for the Taseko site.

'It's a spiritual place'

Later, they said Taseko mine officials arrived and spoke with Tsilhqot'in Chief Joe Alphonse, who told them they did not have consent to conduct work in the area, which includes two lakes considered sacred.

"That's our church," Alphonse told CBC News in an interview.

"We don't go to the Vatican and start breaking walls ... It's a spiritual place that's respected and left alone."

The Tŝilhqot’in's six-member bands have long opposed Taseko's proposed New Prosperity copper-gold mine in the Chilcotin, west of Williams Lake. (Tŝilhqot’in National Government:/Contributed)

According to a statement from the Tsilhqot'in Nation, Taseko Mines Ltd. indicated it would begin using heavy equipment such as logging and road-clearing equipment starting Tuesday.

Taseko says these preliminary activities are an attempt to prove the lakes will not be harmed by the proposed open-pit copper and gold mine. The work involves gathering rock and soil samples.

"We hope to learn from that ... how we can ensure the water quality of the site and [have] environmental integrity," said Taseko's Battison.

"The work is routine, it's commonplace. It's work that is very similar to work that has already taken place at that site," said Battison, who notes the company hoped to start the work two years ago, before a lengthy legal battle began.

The mine was approved by B.C. in 2010 but rejected twice by the federal government on the grounds it would cause adverse environmental effects.

A decision by B.C.'s Supreme Court last August allowed Taseko to proceed with investigative work around the site of the proposed mine, and the Supreme Court of Canada refused to hear the Tsilhqot'in Nation's appeal of that decision last month.

'This is a dead-end project'

Tsilhqot'in Nation leaders say Taseko Mines does not have the nation's consent to undertake the investigative work and that B.C.'s approval of the drilling is a rejection of the United Nations Declaration on the Rights of Indigenous Peoples.

Tŝilhqot’in Nation announces peaceful action to protect Teẑtan Biny and Yanah Biny <br> <a href="https://t.co/gJWdVQWe3P">https://t.co/gJWdVQWe3P</a> <a href="https://t.co/xKavIPjePi">pic.twitter.com/xKavIPjePi</a> —@tsilhqotin

"This is not a green light to get this mine approved," said Alphonse of the Tsilhqot'in National Government, which represents six Tsilhqot'in communities in the area, in an interview Monday.

"The results of this [drilling] project are not going to overturn the two federal environmental appeal processes. This is a dead-end project and you're going into an area that — repeatedly we continue to point out — is our sacred area."

'The work can and will proceed'

Battison says the copper-gold deposit is one of the 15 largest in the world. He said amidst mill closures and job losses, the mine will become an "economic engine" in central B.C.

A day after Taseko workers were turned away at the Tsilhqot'in roadblock, Battison said the company hadn't yet decided how to proceed. He said a court injunction was one of the options.

In a written statement posted last month, Russell Hallbauer, president and CEO of Taseko, said that "the legal challenges are over, the permit is sound, the work can and will proceed."