A Ukrainian International Airlines plane that crashed shortly after leaving Tehran on Wednesday, killing all 176 people on board, was reportedly on fire before impact, according to Iran's civil aviation authority.
Ali Abedzadeh, head of the National Aviation Authority, said in a statement that eyewitnesses had reported that the Kyiv-bound Boeing 737-800 plane was on fire immediately before the crash.
The plane's trajectory indicated it was initially heading westward, turning right after the problem and was on its way back to a nearby airport at the time of the crash, Abedzadeh said.
He said no radio messages were received by the pilot regarding unusual circumstances. The aircraft had risen to an altitude of 8,000 feet after taking off from the Imam Khomeini Airport before disappearing from radar, he added.
The loss of the Ukrainian International Airlines Flight 752 occurred amid heightened tensions and open hostilities between the U.S. and Iran and the reasons for the plane's crash are under greater scrutiny.
Reuters reported, citing five anonymous security sources, that Western intelligence agencies believe the plane had suffered a technical malfunction and not been brought down by a missile.
Under international law, the country where the crash occurred controls the investigation and there have been reports Iran has refused to hand over the black box flight recorders to Boeing or U.S. aviation authorities — agencies that would usually participate in an investigation into a crash of a U.S.-manufactured plane.
The head of the Iran's civil aviation agency said Wednesday that black box recorders had been handed over to the accident investigator and that the initial information on the crash had been passed to Ukraine, the U.S., Sweden and Canada with a number of victims coming from the latter two countries.
Thursday has been declared a national day of mourning in Ukraine following the crash which killed 167 passengers and nine crew members.
Ukrainian President Volodymyr Zelensky urged people to refrain from "manipulation, speculation, conspiracy theories and hasty evaluations regarding the Iran plane crash" on Thursday.
He said he would speak to his counterpart in Iran to step-up cooperation to establish the truth about the plane crash.