The United Nations agency for civilian aviation is sending a letter to Iran after Canada asked it to press Iranian investigators to swiftly analyze the contents of Flight PS752's black boxes — or turn the flight recorders over to a country that can.

Iran admitted it "mistakenly" shot down the Ukrainian International Airlines flight over Tehran on Jan. 8, on a night of intense military activity in the region. Of the 176 people killed in the plane crash, 57 were Canadian citizens and 29 were permanent residents.

Transport Minister Marc Garneau told reporters today he met with the president of the International Civil Aviation Organization (ICAO) to talk about about the delay in completing the black box analysis.

"We would like the black boxes to be analyzed as soon as possible," said Garneau outside of the House of Commons. "It's been almost four weeks."

Transport Minister Marc Garneau: "Iran started off on a very good footing. We need them to continue on that footing." (Adrian Wyld/Canadian Press)

Garneau asked the agency to find out if Iran is following international requirements for plane crash investigations. Under the terms of the international convention on civil aviation, the country leading a crash investigation is expected to "arrange for the read-out of the flight recorders without delay." Those terms also say that if a country doesn't have "adequate facilities" to read the flight recorders, it should turn to another country for help.

ICAO confirmed to CBC News it's now looking into reports that Iran isn't complying with the convention.

"Our council president is conveying in a letter to Iran's civil aviation authority to confirm if this is the case, and to remind it of its relevant obligations under Annex 13 to the Chicago Convention," said the agency's spokesperson Anthony Philbin in a media statement.

Canada is pushing to fully participate in the investigation into the downing of the Ukrainian International Airlines flight 752. (Ukrainian Presidential Press Office via The Associated Press)

Trudeau said Iran lacks technical expertise

Prime Minister Justin Trudeau said yesterday in French that an independent, robust aviation investigation must move to analyze the black boxes as quickly as possible.

Trudeau said it's "extremely worrying" that Iran is trying to analyze the flight recorders itself when it lacks the technical resources.

Garneau said he raised similar concerns with his counterpart in Iran yesterday.

"I encouraged him to move ahead expeditiously," he said. "I told him we did not believe they have the necessary expertise and equipment in order to do the analysis and the decoding of the boxes, which may be damaged."

Garneau said he asked Iran's Transportation Minister Mohammad Eslami to look into sending the two flight data recorders to France, adding that Canada also wants to participate in the analysis. He said Iran asked Canada to send it an official letter about the matter.

Canada also is continuing its efforts to get Iran to give Canadian crash experts a higher level of accreditation in the official investigation. Trudeau said he wants Transportation Safety Board investigators to fully participate in the investigation.

Earlier this month, Iran did allow two TSB investigators to spend six days in Iran inspecting the wreckage, visiting the crash site and receiving updates on the investigation. Iran also asked for Canada's help with downloading and analyzing the data recorders.

Two other TSB specialists have been waiting on standby to deploy to Iran, but Iran still hasn't announced when and where that work will happen.

"Iran started off on a very good footing," said Garneau. "We need them to continue on that footing, especially with respect to the analysis of the black boxes. We're going to continue pushing it. I'm confident that it's going to happen."