RT - Kiev will establish if its airliner, which crashed near Tehran with 176 on board, was hit by a �Russian-made� missile, collided with a drone, or was targeted by terrorists, a Ukrainian security council official has said.

Ukraine has sent dozens of investigators to Iran to look into possible causes of the crash, including �an explosion inside the plane following a terrorist attack,� collision with an unmanned aerial vehicle, or a direct hit by �a surface-to-air missile,� Oleksiy Danilov, secretary of the security council, told Censor news outlet.

Kiev is now in talks with Tehran regarding access to the crash site, the official added. They said investigators will search it for any �wreckage of a Russian-[made] Tor missile,� referring to allegations that popped up on social media.

That claim may not sit well with Iran�s preliminary findings, which it disclosed earlier in the day. The country�s civil aviation authority said the Boeing 737-800, operated by Ukraine International Airlines, caught fire when it was airborne. Pilots tried to return to Imam Khomeini airport from which they departed, but to no avail. They made no distress calls during the emergency, it has emerged.

On Wednesday, Ukraine had initially suggested that the crash was due to an engine fire or another technical issue, but later retracted the statement. Meanwhile, President Volodymyr Zelensky cautioned the public against spreading conspiracy theories and speculating on what could have cause the crash � which has already been named the deadliest in the history of modern Ukraine.