Iran has agreed to send black box recorders from a downed Ukrainian jetliner to Kiev for analysis, an Iranian official said on Wednesday, in a move that would end a two-month standoff.
Top Iranian officials have until now refused to hand over the flight recorders from the Ukraine International Airlines flight, which was shot down by the Iranian military on January 8, killing all 176 people on board.
Farhad Parvaresh, who leads Iran's delegation at the UN's International Civil Aviation Organisation in Montreal, said Tehran's aviation authority also invited other interested countries to take part in reading the data.
This effectively opens the door to the US, Ukraine, Canada and the UN agency, sources said.
Air crash investigations are usually left to the agency's 193 member states.
Canadian Foreign Minister Francois-Philippe Champagne said the move was a step in the right direction.
"We welcome those words but we will obviously judge Iran by their actions," Mr Champagne said.
Ottawa has repeatedly urged Iran to hand over the damaged boxes from the crash in which 57 Canadians died.
Iran had also made clear that it would transfer the boxes to France if need be, Mr Champagne said.
Canadian Prime Minister Justin Trudeau urged Iran in January to send the recorders to France, one of the few countries with the ability to read damaged black boxes.
Andriy Shevchenko, the Ukrainian ambassador to Canada, tweeted that the announcement was "an important result".
Under UN rules, Iran retains overall control of the investigation while the US and Ukraine are fully accredited, because they are the countries where the jet was built and operated.
Canada is on a lower rung of official access as the home of many of the accident's victims, but in practical terms it is expected to have an active role after strong pressure from Mr Trudeau, safety experts said.
"We will have our experts there so we can better assess if there was any tampering with the black boxes," Mr Champagne said.
It remains unclear how much cooperation there would be between the US and Iran in the investigation, with relations at their lowest point in years.
Salvatore Sciacchitano, president of the UN agency's governing council, welcomed Iran's confirmation of its intention to have the black boxes analysed in Ukraine or France.