UK demands full probe into Iran air crash, even US officials say it was downed by missiles

British Prime Minister Boris Johnson called Thursday for a "full, credible and transparent" investigation into how a Ukrainian passenger plane crashed in Iran, killing all 176 people on board.

A spokesman said reports about what happened were "very concerning", after a Ukrainian security official said investigators were pursuing several les, including possibility of a surface-to-air missile strike.

Johnson spoke to Ukrainian President Volodymyr Zelensky in a phone call in which he offered his condolences for loss of life and received an update on Ukraine's efforts to establish facts, spokesman said.

" prime minister said that re needed to be a full, credible and transparent investigation into what happened," spokesman said.

He ded: " reports we have seen are very concerning and we are urgently looking into m." 

Ukraine International Airlines (UIA) Boeing 737NG went down on Wednesday, shortly after Tehran launched missiles at US forces in Iraq in response to killing of a top Iranian general in a US drone strike in Baghd.

RE | Iranian Missiles Could Have Shot Down Ukraine Flight By Mistake, Report US Sources

Oleksiy Danilov, secretary of Ukraine's National Security and Defence Council, told AFP that investigators were looking at a number of les.

se include a collision with ar airborne object, a rocket from Iran's missile defence system, an engine explosion caused by a technical problem, and an explosion on board aircraft due to an "act of terror", he said on Facebook.

Danilov told AFP that for moment re was reason to believe that airliner h been hit by a missile.

In Kiev, Ukrainian presidency said Zelensky invited Britain to join probe, and also called for a "transparent, thorough and objective investigation that can quickly establish facts of this trdy".

(Im credits: Getty)