Ukraine leader does not rule out missile in crash
Zelenskiy reiterated his call for "all international partners" - the US, Britain and Canada in particular - to share data and evidence relevant to the crash.
He also announced plans to discuss the investigation with US Secretary of State Mike Pompeo on Friday afternoon.
Western leaders have said the Boeing 737 appeared to have been unintentionally hit by a surface-to-air missile near Tehran hours after Iran launched ballistic missiles at two US bases in Iraq to avenge the killing of its top general in an American air strike.
Meanwhile, Iran's civil aviation chief denied Friday that a missile downed a Ukrainian airliner which crashed killing all 176 on board, dismissing claims of a catastrophic mistake by Tehran's air defences.
The declaration at a press conference in the Iranian capital came after Britain and Canada pointed to what they said were signs of an accidental missile strike.
"One thing is for certain, this airplane was not hit by a missile," Iran's civil aviation chief Ali Abedzadeh said.
Canadian Prime Minister Justin Trudeau said Thursday that multiple intelligence sources indicated that an Iranian missile downed Ukraine International Airlines Flight PS752 after it took off from Tehran.
But Abedzadeh rejected the allegation, saying that "any remarks made before the data is extracted (from the plane's black box flight recorders) ... is not an expert opinion".
Trudeau's comments came as video footage emerged that appeared to show the moment the airliner was hit.
The footage, which The New York Times said it had verified, shows a fast-moving object rising at an angle into the sky before a bright flash is seen, which dims and then continues moving forward. Several seconds later an explosion is heard.
Citing information from allies as well as Canada's own intelligence, Trudeau said the plane appeared to have been hit by an Iranian surface-to-air missile.
"We know this may have been unintentional. Canadians have questions, and they deserve answers," Trudeau told reporters.
The US National Transportation Safety Board said late Thursday it had received formal notification of the crash from Iran and would send a representative to join the investigation.
Iran's foreign ministry earlier invited US plane maker Boeing to "participate" in the probe.
Read more: Missile attack or engine failure? The possible causes of the Iran plane crash explained
The flight went down in the dark just minutes after takeoff, with no radio message from the pilot to indicate distress, according to the Iranian Civil Aviation Organization.
It was carrying 82 Iranians, 63 Canadians, 11 Ukrainians, 10 Swedes, four Afghans, three Germans and three Britons.
With tensions high between the United States and Iran, the disaster unfolded just hours after Tehran launched ballistic missiles towards bases in Iraq housing US troops.
Iran retaliated for the 3 January US drone strike in Baghdad that killed a top Iranian general.