The recordings, aired on Ukraine's 1+1 TV channel on Sunday, feature a conversation between an air traffic controller and the pilot of another plane at the time the Ukrainian airliner was hit on January 8, killing all 176 people on board.

The pilot can be heard describing "the light of a missile" on its route and then an explosion.

Iran initially denied Ukraine International Airlines (UIA) Boeing 737 had been brought down by one of its missiles.

It later admitted that two missiles were fired at the plane by air defences on high alert, hours after Iranian armed forces fired ballistic missiles at US troops stationed in Iraq.

Ukrainian President Volodymyr Zelensky said after the release of the recording that it "proves that the Iranian side knew from the start that our plane was hit by a missile.

"Everything is audible there," Zelensky told 1+1. "Everything is recorded."

- 'It's the light of a missile' -

The audio clip features the pilot of an Aseman Airlines flight from Iran's southern city of Shiraz to Tehran communicating with air traffic control in the Iranian capital.

"There is a series of lights on our route, like a missile. Is there something?" the pilot is heard asking.

"What is the light like?" the controller asks.

"It's the light of a missile," the pilot replies.

The control tower then tries unsuccessfully to contact the Ukrainian airliner.

After a few minutes the pilot says: "There was an explosion. We saw a very bright light here."

It was unclear how the channel obtained the recording, but officials denied it had come from the Ukrainian authorities.

"This is a journalistic investigation. You need to ask them where they got this recording," Oleksiy Danilov, secretary of Ukraine's Security and Defence Council, told AFP.

UIA president Yevgeniy Dykhne said it was important "not to create another sensation" around the catastrophe, but to join efforts "to ensure thorough and complete investigation" of the crash.

The downing of the airliner came in the days following the US assassination of a top Iranina commander, Qasem Soleimani, near Baghdad's airport.

Iran responded with a barrage of missiles at two US bases in Iraq, in what was seen as an attempt to prevent a spiral of escalation.

But hours later, an Iranian Revolutionary Guard unit mistakenly shot down the Ukrainian passenger jet, in what Iranian President Hassan Rouhani called a "human error".

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