Iran is refusing to give the United States or Boeing the black boxes of the Ukrainian plane which crashed outside Tehran on Wednesday.
All 167 passengers and nine crew members on the Boeing 737-800 aircraft perished when the plane crashed into a field in Iran, only hours after the Middle East nation attacked Iraqi military bases housing US troops.
The cause of the air crash was initially reported astechnical in nature, but an investigation is now underway with Ukranian authorities offering assistance. Ukrainian President Volodymyr Zelensky says the priority is to "establish the truth and those responsible for this terrible catastrophe".
Two black boxes which could help in the investigation are currently being examined by Iran, but they won't be handed over to planemaker Boeing, according to Iranian media cited by Reuters. Under international rules, an investigation into a plane crash is to be held by the nation in which the crash occurred.
"We will not give the black boxes to the manufacturer and the Americans. It's not yet clear which country the black box will go to for the investigation," said the head of Tehran's civil aviation organisation, Ali Abedzadeh.
"This accident will be investigated by Iran's aviation organisation but the Ukrainians can also be present during the incident's investigation."
Among those killed in the crash were 82 Iranians, 63 Canadians and 11 Ukrainians. There were also three Brits onboard. Representatives from countries with citizens killed have said they are monitoring the situation.
Flight data from the airport showed once the plane took off, it stopped sending data almost immediately afterward, according to website FlightRadar24. The flight was bound for Kyiv, Ukraine.
Following the crash, Ukraine International Airlines suspended all flights to Tehran.