WINNIPEG -- Canada is keeping up the pressure on Iran to involve outside experts in the investigation into downed Ukrainian jetliner PS752, amid signs that Iran is balking at turning over the flight data recorders.

Foreign Affairs Minister Francois-Philippe Champagne wrote Sunday to his Iranian counterpart to stress Canada's view that the black boxes should be sent quickly for analysis by experts in either France or Ukraine.

He said that's the consensus of the countries who lost citizens on Jan. 8, when Iran's Revolutionary Guard accidentally shot down the passenger plane, killing all 176 aboard, including 57 Canadians.

Champagne, who met personally with Iranian Foreign Minister Mohammad Javad Zarif on Friday in Oman, said he stressed that "Iran has a path to choose."

"When you say to the world that you take full responsibility, that comes with consequences," he said, adding that includes being fully transparent about the investigation.

Champagne was speaking on his way into a three-day cabinet retreat in Winnipeg amid reports the Iranian official leading the investigation appears to be backtracking on an earlier statement that the black boxes would be sent to Ukraine.

Hassan Rezaeifar was quoted Sunday by the state-run IRNA news agency as saying "the flight recorders from the Ukrainian Boeing are in Iranian hands and we have no plans to send them out."

He said Iran is working to recover the data and cabin recordings, and that it may send the flight recorders -- commonly known as black boxes -- to Ukraine or France. "But as of yet, we have made no decision."

On Saturday, the same official was quoted by the semi-official Tasnim news agency as saying the recorders would be sent to Ukraine, where French, American and Canadian experts would help analyze them. Iranian officials have previously said the black boxes were damaged but are usable.

It was not immediately possible to reconcile the conflicting accounts. Iran may be hesitant to turn over the recorders for fear that more details from the crash -- including the harrowing 20 seconds between when the first and second surface-to-air missiles hit the plane -- will come to light.

Hours earlier, the Guard had launched ballistic missiles at U.S. troops in Iraq in response to the U.S. airstrike that killed Iran's top general in Baghdad. Officials say lower-level officers mistook the plane for a U.S. cruise missile.

Canada's Transportation Safety Board issued a statement this morning saying it understands the black boxes are still in Iran and that officials from Iran's aircraft accident investigation bureau may travel to Ukraine this week to meet with the Ukrainian plane crash investigators to discuss the investigation and visit the Ukrainian recorders lab.

Two Canadian air-crash investigators who have been working on the investigation left Tehran early Sunday morning and will head to Ukraine to meet with that country's air accident investigation agency and collaborate as best they can to help further the probe.

During their six days in Tehran, the Transportation Safety Board (TSB) investigators had several meetings with officials from the Iranian aircraft investigation bureau, visited the accident site and examined the wreckage, which is secured in a separate location.

The TSB said there are still no firm plans as to when and where the aircraft recorders will be downloaded and analyzed.

A second team of Canadian investigators who specialize in downloading and analyzing aircraft recorder data will be deployed once it is clear when and where that work will be done, the TSB said.

Meanwhile, at a memorial event in Montreal, some of the victims' families expressed frustration over the lack of answers.

In front of a table strewn with flowers and covered in framed photos of victims, Armin and Arash Morattab said their grief has been mixed with anger ever since they learned the plane was downed.

"What we would ask today, on behalf of our family justice is to know what has happened before the tragedy, who is responsible for that," said Armin Morattab, who lost his twin brother Arvin and his wife, Aida Farzaneh.

His brother Arash said he and many in the community don't trust the Iranian government, whose denial of complicity in the first days following the crash amounted to "killing my brother and Aida again," he said.

He said the family won't be able to move on until they get answers.

"That's the only thing that can make our lives a bit calmer," he said. "I can't get calm by crying or being sad or any of these things. Everything has changed now."

This report by The Canadian Press was first published Jan. 19, 2020.

With files from Morgan Lowrie in Montreal and the Associated Press.