OTTAWA -- Tracts of land that had been set aside for reindeer grazing in Canada's North have instead been offered up by the Conservative government for oil and gas exploration, newly released documents show.

Companies interested in obtaining petroleum exploration rights in the Mackenzie Delta and Beaufort Sea region of the Northwest Territories were asked last year to nominate blocks of land that they wanted to see included in a subsequent call for bids.

Reindeer-grazing reserves near the communities of Inuvik and Tuktoyaktuk were among the lands that were included in that call for nominations, pending a necessary amendment to an order-in-council imposed in 2010.

Documents show officials at Aboriginal Affairs and Northern Development Canada have discussed just such an amendment in order to allow the reindeer-grazing land to be included in the bidding for exploration licences.

"Most Crown lands in the Mackenzie Delta are withdrawn from disposal under an order-in-council to allow for a reindeer-grazing reserve," says a briefing note to a top department official from last August.

"These lands have been included in the call for bids, pending amendments to (the order-in-council) to confirm the Crown's ability to dispose of these lands for oil and gas exploration.

"While the timing of these amendments remain uncertain, should these lands become available for issuance they may be included in the call for bids and a note to potential nominators is included in the call to this effect."

The Canadian Press obtained the documents under the Access to Information Act.

Aboriginal Affairs Minister Bernard Valcourt's office said the move is part of the government's effort to balance resource development with environmental protection.

"The government of Canada continues to deliver on initiatives under the Northern Strategy to realize the economic and social aspirations of Northerners," spokeswoman Erica Meekes said in an email.

"This includes issuing exploration licenses in the North while implementing measures that ensure the protection of our Northern environment."

While the reindeer-grazing reserve land was included in last year's call for nominations, the government says no companies have asked to bid on it.

The Mackenzie Delta region is a trove of oil and natural gas. After decades of starts and stops, the National Energy Board in 2011 approved a 1,200-kilometre natural gas pipeline that would start at the Beaufort Sea and continue south through the Mackenzie Valley to the northern Alberta boundary.

The region hasn't always been home to reindeer. In the late 1920s, caribou became scarce and the people of the Mackenzie Delta, who depended on the caribou for food, began to starve.

So in the early 1930s, the Canadian government bought some 3,000 reindeer from a company in western Alaska and hired Sami herders from northern Europe to bring the animals to the delta, thousands of kilometres away.

When they finally reached their destination, the herders taught the locals how to care for the reindeer.

The program never really took off, but descendants of the original herders remain there today.

One of them, Lloyd Binder, a reindeer herder from the Mackenzie Delta region, said any concerns about opening the land to oil and gas exploration would likely be "streamrolled."

"We can work around it, I think," Binder wrote in an email. "We are in the survival business and oil/gas will run out in a decade or three!"