Canada's largest private sector union has been dealt a blow in its long legal battle with a Walmart store in Saskatchewan that is the retail giant's only unionized outlet in the country.

The Supreme Court of Canada said Thursday it would not hear the United Food and Commercial Workers' appeal of decisions by the Saskatchewan Labour Relations Board on union accusations of unfair labour practices.

That means an application to decertify the union at the store in Weyburn will proceed and will include votes already cast by employees. The votes were set aside until the court decision.

"We are pleased with the court's decision," said Andrew Pelletier, Walmart Canada's vice-president of corporate affairs.

"Our associates in Weyburn voted more than 2 1/2 years ago in a secret ballot on whether or not they wanted to be represented by the union, and they are still waiting for their votes to be counted."

More than 80 employees at the Weyburn store cast ballots in a decertification vote on Dec. 22, 2010.

The ballots are to be officially tallied Friday at the labour board office in Regina.

Norm Neault, president of UFCW Local 1400, said the union is disappointed the high court will not hear the appeal.

He said if the decertification vote fails, the union will continue to seek a contract for its members who work at the Weyburn store.

If it succeeds, the union will have to accept the loss, Neault said, but won't give up its fight against U.S.-based Walmart, the world's largest retailer with more than 11,000 stores in 27 countries.

"It is not over yet," he said.

"We are going to continue to keep up the good fight and make sure that we are able to organize Walmart and bring the type of wages and benefits to the workers that they deserve."

The union first applied for certification at the store in southeastern Saskatchewan in 2004.

The application was granted in 2008, but was challenged by Walmart and overturned in Court of Queen's Bench the following year.

The Saskatchewan Court of Appeal dismissed an appeal by the union in December 2012 and ruled that ballots cast by the Weyburn store employees should be counted. The union then sought leave to appeal to the Supreme Court.

This is the latest legal victory by Walmart Canada over the union.

In November 2009, the Supreme Court ruled Walmart was within its rights when it shut down its store in Jonquiere, Que., in 2005 -- one year after workers there won union certification.

The company said it closed the store because it wasn't profitable and after a year of bargaining failed to lead to a collective agreement. Almost 200 people lost their jobs.

Some of the unionized employees fought the closure in court.

Neault said he believes what happened at Jonquiere may have frightened some of the employees in Weyburn.

"They (Walmart) have a lot of resources, and I don't think you have to look any further than Jonquiere, Que., and see what happened there, and how that plants things in the minds of individuals," he said.

The Weyburn store is one of 380 outlets in Canada and the only one that is certified.

Walmart employee Gordon Button, 71, helped organize the application to decertify the union at the Weyburn store and was jubilant that the ballots cast in the vote will finally be counted.

"This is what we have been hoping for for a long time," he said. "We want it to be done and over with."

Button, who was hired five years ago, said he earns $12.50 an hour and works about 36 1/2 hours a week. He said the push to decertify had nothing to do with fear that Walmart might close the Weyburn location.

He said it was more the case that he and some of his co-workers didn't believe the union when it said it could help them earn higher wages.

"We couldn't see that it would be any benefit to us," he said.

"We already have some benefits -- a pension plan and a medical thing that you can pay into a little bit. You get a bonus every year if you do a good job."

The union has been attempting to certify Walmart stores in other Saskatchewan communities, including Moose Jaw and North Battleford.

Walmart operates more than 4,600 stores in the United States. None of them is unionized.

As is standard practice in the case of applications for leave to appeal, the Supreme Court did not give reasons for its decision.