Yukon First Nations say they are "looking at their options" after Bill S-6, a controversial piece of legislation that amends the Yukon Environmental and Socio-economic Assessment Act, was passed last night in the House of Commons.

The bill has been contentious for over a year, with Yukon First Nations saying it undermines their Umbrella Final Agreement, with governments saying four amendments to the bill opposed by First Nations are necessary to attract business to the territory. The Coalition of Yukon First Nations have previously threatened a lawsuit if the bill passes.

Members of Parliament voted 148 in favour of the bill, with 125 opposed.

All MPs voting in favour were members of the Conservative caucus, including Yukon MP Ryan Leef. The bill was opposed by all voting MPs that were not members of the ruling Conservative party.

In a statement Tuesday morning, 11 Yukon First Nations, as well as the Council of Yukon First Nations, said they are "very disappointed Bill S-6 has passed without amendments.

"We have made every effort and exhausted every avenue to work collaboratively with Canada to resolve our concerns," the statement reads. "We will continue to protect the integrity of our Agreements are are looking at our options now that Canada has made its decision."

Tim Koepke, a former chief land claim negotiator for the federal government, says that he's disappointed the federal government is changing the Assessment Act.

"The development assessment process was designed by Yukoners to fit the specific needs," he said. "We put a lot of care and effort. We brought a lot of experts in, and that was enshrined in that agreement.

"So it's disappointing to the First Nations, and, frankly, to us who negotiated that development assessment chapter, that this has now changed by uniliteral action."

The bill is now awaiting Royal Assent before it becomes law.