OTTAWA -- Canada has asked for international help to pressure Iran to give up the black boxes recovered from the wreckage of Ukraine International Airlines Flight PS752, says Foreign Minister Francois-Philippe Champagne.

He and Transport Minister Marc Garneau have met the leaders of the International Civil Aviation Organization (ICAO), which is based in Montreal, to try to break a logjam over the data recorders.

Iran retrieved the data recorders but doesn't have the equipment to extract the information from them. Champagne said Canada wants the black boxes sent to France for analysis, while Iran has asked other countries to lend it the gear so it can do the analysis itself.

"Obviously we're standing up for the families -- we'll always do that. Not only we're standing up as Canada, but I think now the world is watching and saying, 'Hold on for a minute, there's an international convention to which Iran is a party to, and now they have to abide by that.' And that's why we're going to the UN body," Champagne said.

Champagne said he would be having a telephone conversation with the Iranian foreign minister Wednesday afternoon.

"We are going to be talking about the black box. Obviously, we are going to be talking about the investigation, we are going to be talking about compensation," Champagne said.

Iran admits its air defences shot missiles at the plane in January, saying troops mistook the civilian airliner for something hostile. Tensions were high: Iran had just fired ballistic missiles at American and coalition bases in neighbouring Iraq in retaliation for the U.S.'s killing of Iranian general Qassem Soleimani in Baghdad.

All 176 people aboard the Ukrainian plane, including 138 who were headed for Canada, were killed when it crashed outside Tehran. Fifty-seven of them were Canadian citizens and 29 more were permanent residents. Many were students and academics returning to Canada after spending the December break in Iran.

Because the crash was in Iran, its own aviation authority has command of the investigation, but it's supposed to follow ICAO guidelines for conducting it. Among other things, those say that black boxes should be "opened" and analyzed without delay.

"Now we're close to a month and we're going to be making sure the Iranian regime understands," Champagne said.