A Canadian judge has quashed a petition for an independence referendum in Alberta after finding First Nations were not consulted, dealing a blow to separatist hopes in the country’s western province.

Justice Shaina Leonard of the Court of King’s Bench on Wednesday shut down the effort by a separatist group to hold a referendum on secession from Canada.

Leonard said Alberta’s provincial government had an obligation to consult with First Nations before allowing organizers to collect signatures.

Two First Nations groups argued that any referendum would violate their treaties with the Crown, which predate the creation of Alberta.

“As a matter of logic and common sense, there can be no doubt that Alberta’s secession from Canada will have an impact on Treaties 7 and 8,” the judge wrote in her decision.

The decision also looked at legislation passed by the Alberta government that removed the requirement that referendum questions be constitutional, and the right of the chief electoral officer to refer proposals to the courts for review.

Leonard said the separatists should not have been allowed to reapply because the chief electoral officer denied their first proposal.

Two weeks ago, separatists had triumphantly delivered boxes with more than 300,000 signatures in favour of the proposed referendum. But days later, the effort was rocked by revelations that a separatist-linked group had illegally gained access to private elections data, prompting investigations from both elections officials and police.

The leader of Athabasca Chipewyan First Nation, which joined others in challenging the legitimacy of the separatist petition, said Wednesday’s ruling “reinforces the importance of treaty rights, meaningful consultation, and the recognition of the serious impacts decisions like these” would have on First Nations communities.

“This decision should close the chapter on the suggestion of an independence referendum. The court has spoken – and so have the First Nations,” chief Allan Adam said.

Alberta’s premier, who says her government is pro-Canada but has taken steps to aid separatists, vowed to challenge the ruling.

“This is a decision by one judge,” said Danielle Smith. “We think that this decision is incorrect in law and anti-democratic, and we will be appealing it as a result.”

Earlier in the day, Smith said the citizen-led petitions were an “important” democratic tool.

“Whether the government likes the citizen initiative petition questions that are put forward or whether we don’t like them, we believe the process should allow all voices of Albertans to be heard,” she said.

Separatist leader Mitch Sylvestre, who led the effort to collect more than 300,000 signatures, said he would lobby Smith to use government’s powers to put the question on the October referendum.

While the government could add a question on separation, skirting the petition process, such a move would probably face the same challenge from First Nations.

Shortly after learning of the judge’s decision, Jeffery Rath, a lawyer who represents the separatists, said the decision featured “numerous errors in law throughout” and “breaches of the rules of natural justice”.

Both Rath and the provincial government suggested there was not a duty to consult with First Nations.

“The law requires consultation in the context of amendments to the Canadian constitution that involves the devolution of federal power to the provinces that affects First Nations,” Rath said. “From our perspective no rules were broken.”