All 176 people on board died when Ukraine International Airlines (UIA) Boeing 737NG went down on Wednesday, shortly after Tehran launched missiles at US forces in Iraq in response to the killing of a top Iranian general in a US drone strike in Baghdad.

"If any country has information that can help conduct a transparent and objective investigation into the tragedy, we are ready to receive it and cooperate in further verification," the Ukraine presidency said in an English-language statement.

"Ukraine is interested in finding the truth. Therefore, I ask all our international partners: if you have any evidence to assist the investigation, please provide it."

Investigators are pursuing several leads following the crash of the Ukrainian passenger plane in Iran, including a surface-to-air missile strike, an act of terror and engine failure, Oleksiy Danilov, the secretary of Ukraine's national security and defence council (RNBO), told AFP earlier Thursday.

The council is tasked with coordinating the probe into the disaster, the first fatal crash involving Ukraine's biggest carrier UIA.

US President Donald Trump said Thursday he had "suspicions" about the crash as unnamed officials told American media that Iranian air defence systems likely accidentally shot down the airliner.

Newsweek, CBS and CNN said that satellite, radar and electronic data indicated the tragic error, which followed a ballistic missile barrage by Iran on two military bases in Iraq where US troops work.