The Conservative Party of Canada offered an explanation Monday as to why it issued a threatening letter to the widow of an asbestos victim: it was standard legal procedure.

The Tories demanded that the woman stop using the party’s official logo in her anti-asbestos ad campaign — and warned that she risked “further action” if she failed to comply.

“We send out a letter any time someone uses our logo without permission,” party spokesman Fred DeLorey said in an email Monday.

“It is a step we are required to take whenever we discover there is an unauthorized use of our logo.

“We have nothing further to add to this.”

This latest dispute in Canada’s debate over its declining asbestos industry comes as the Quebec government mulls whether to help relaunch one of the country’s only remaining mines.

The Conservatives under Prime Minister Stephen Harper have been adamant defenders of Canada’s declining asbestos-mining industry, despite growing concern from health experts around the world.

Michaela Keyserlingk, whose husband Robert died in 2009 of a cancer linked to asbestos exposure, is running an online banner ad that reads, “Canada is the only western country that still exports deadly asbestos!”

It features the Tory logo — a blue letter C with a Maple Leaf — and also links to her website which contains information, news stories about asbestos and a personal essay about her husband’s battle with mesothelioma.

Keyserlingk said Monday that she’s received a wave of supportive emails since going public with the Tory warning.

The Ottawa resident acknowledges that she doesn’t have permission to use the party’s symbol, but insists she’s not going to remove the ad until she meets with a senior member of the Conservatives to discuss the future of Canada’s asbestos industry.

The Tories want the ad taken down — right away.

In his email to Keyserlingk, Conservative executive director Dan Hilton wrote: “It has come to our attention that your organization is currently using a trademark of the Conservative Party of Canada in your advertising material. This usage is unauthorized and must cease immediately. Failure to do so may result in further action. Please govern yourself accordingly.”

But one trademark law expert doesn’t believe the Tories would have a solid legal footing against Keyserlingk in court, especially since she’s not trying to profit from the logo.

“On a trademark basis, I don’t think it’s a particularly strong case,” said Teresa Scassa, who holds a Canada Research Chair in information law at the University of Ottawa.

“And I think it’s fair to say that we do want to be careful about unduly restricting freedom of expression.”

Scassa, who just published a book on Canadian trademark law, said the party might have a more effective argument if the logo had copyright protection — meaning the party could therefore claim the ad is infringing on an original artistic work.

Either way, she thinks taking legal action would involve significant political risk.

“What does the Conservative party stand to gain from telling a woman whose husband died from asbestos-related cancer that she’s limited in how she objects to the Conservative government’s policy on asbestos?” Scassa asked.

Keyserlingk’s husband was the former president for the Ottawa-Centre Progressive Conservative riding association. She said he would have been disgusted by the actions of his old party.

Other politicians expressed concern Monday over how the Tories approached Keyserlingk’s case.

New Democrat Pat Martin, a former asbestos miner and vocal critic of the industry, applauded Keyserlingk’s decision to stand her ground and argued that “civil disobedience” can sometimes have a positive impact.

“I hope they do sue her because, believe me, there’ll be a large community that rushes to her side and it will just further expose the hypocrisy of the Conservatives,” Martin said in an interview.

“It would be the dumbest move they could ever make, frankly.”

The mayor of Sarnia, Ont., meanwhile, reacted to Keyserlingk’s story by writing a letter to the Conservatives.

“Your actions on the asbestos issue … with threatening a widow whose husband died of exposure to asbestos are absolutely shameful,” Bradley wrote in an email to the party Sunday.

“I invite you to come to Sarnia Lambton and see the devastating impact asbestos has had on countless lives of the people of this community and why it is morally wrong for Canada to support and promote the export of asbestos.

“I look forward to hearing from you.”

Bradley added in an interview Monday that many residents of his industrial city of 70,000 were exposed to the hazardous mineral and have since been struck by diseases linked to it.

The mayor ran for the federal Liberals in 1984 but insists he has no ties with any party in Ottawa. He has long been critical of the asbestos industry, dating to back to well before the Tories took office.

Sarnia’s council passed a resolution in 2001 calling for an end to Canadian asbestos exports, and the mayor suggests politicians focus on creating new jobs in another sector.

Asbestos proponents maintain the substance is safe when handled properly and argue that the type being mined in Quebec, chrysotile, is far less dangerous than the notorious amphibole variety.

But opponents reject the idea that the substance could be handled safely, according to the strictest standards, in the poor countries that import it.

The Canadian Cancer Society says close to 100,000 people die globally every year because of workplace exposure to asbestos fibres.

Meanwhile Monday, an attempt was afoot to breathe new life into one of Canada’s last remaining asbestos mines.

The Quebec government has already agreed to guarantee a controversial $58-million bank loan to extend the life of Jeffrey Mine in the town of Asbestos for another 25 years, as long as the company can find enough private financing.

The deadline for the deal had been set by the provincial government for Monday, but Quebec accepted a request by investors to have an extension until Oct. 1.

The company says the mining project would create up to 500 jobs in the central Quebec region.