Prime Minister Stephen Harper says Canada will continue to advocate for Canadians imprisoned in Iran despite cutting diplomatic ties with Tehran. But the wife of a Toronto man on death row is not convinced.

Antonella Mega's husband Hamid Ghassemi-Shall has been imprisoned in Iran since 2008, when he was charged with espionage during a trip to visit his mother.

In an interview with CTV's Canada AM, Mega explained that her husband's sister planned to visit him in the notorious Evin prison Monday, to inform him of Canada's decision to cut diplomatic ties with Tehran.

Mega learned of the move in a phone call from consular affairs staff on Friday, she said, recalling their assurances that, "Hamid's case remained important for Canada and they would be advocating for him through other countries."

But those assurances have left her wondering.

"Personally I can't help but think how that will play out in the sense that, since Canada has closed communications with Iran, I'm not sure how Iran will see the case going forward," she said, suggesting direct pressure might be more effective.

Since the surprise announcement Friday -- the same day Canada formally listed Iran as a state sponsor of terrorism -- Prime Minister Harper and Foreign Affairs Minister John Baird have cited the safety of Canada's diplomats there as a key factor in the change of policy.

“This is a regime that, among its many wrongs, does not respect normal practices of diplomatic immunity and protection,” Harper told reporters at the Asia-Pacific Economic Cooperation (APEC) summit in Vladivostok, Russia.

“Whether it is (Iran’s) nuclear program, its support for Assad, its anti-Semitism, its support for terrorism -- it just becomes worse and worse and worse,” he said Saturday.

In an interview broadcast on CTV's Question Period Sunday, Baird denied rumours that the move was spurred by inside knowledge of a specific threat or imminent military action.

“I can confirm that we have no knowledge whatsoever of any outside military action, whether it’s from the United States or from Israel,” Baird said.

“We just felt at this time it is no longer safe and secure to have these Canadians working there and that weighed heavily on me,” Baird said in an interview from the APEC summit in Vladivostok, Russia.

Iran has denounced the move, with the foreign ministry calling the decision hostile, unwise and unconventional and the parliamentary speaker cancelling a visit to Canada that had been slated for October.

Back in Ottawa, Canada's most recent ambassador to Iran said the unexpected decision is of such political importance, it should be debated in Parliament.

John Mundy told Canada AM that he would like to see lawmakers answer two key questions: How Ottawa foresees a peaceful resolution to Iran's nuclear issues, if diplomacy is indeed futile; and also what commitment Ottawa has given Israel in the event of military confrontation.

In the meantime, Mundy says pulling Canadian diplomats out of Iran will have tangible consequences.

Besides cutting off its inside-line of communication with Iran, and losing the ability to monitor developments there from an insider's perspective, Mundy said the ability to directly advocate for Canadians living there has been lost.

"There are a great many Canadians living in Iran," Mundy said, noting that three are imprisoned, two of whom are facing execution.

Ghassemi-Shall, a 43-year-old Toronto shoe salesman and Canadian citizen, was tried, convicted and sentenced to death on espionage charges in 2008.

That same year, Canadian resident Saeed Malekpour was arrested during his own family visit. He was charged and convicted on charges related to Internet pornogrpahy, and also sentenced to death.

Both men were tried without a legal defence, after a torturous interrogation.

But after four years hoping for her husband's release, Mega is not letting souring political relations between Ottawa and Tehran dash her hopes now.

Recounting a telephone conversation with Ghassemi-Shall last week, Mega said: "His spirits were pretty low, although he sounded okay. His concern was there had been some pardons in Iran, which is a very positive thing, however he was not on that list.

"He was pretty sad about that, but I hope that Hamid will also be pardoned soon."