Horrifying new CCTV has emerged showing a Ukrainian passenger jet hitting the ground in a fireball and exploding into pieces near Tehran.
The video was captured by a camera at a home extremely close to the site of the crash, which killed all 176 people on board, including three British passengers.
The footage shows a tremendous explosion as flaming debris is catapulted through the area.
It emerged in Iranian media as Ukraine said it was investigating four potential scenarios to explain the crash – a missile strike, terrorism, a collision with a drone or an engine explosion.
Iranian investigators, who have refused to release the black box recorders, said the plane had suffered an unspecified technical problem and was on fire before it went down just after 6am local time on Wednesday.
Ukraine sent investigators to the crash site to look for possible fragments of a Russian-made missile used by Iran’s military after photos emerged on social media showing part of a rocket.
It has asked Britain to help in the investigation into the cause.
Posts on Twitter claimed the object landed in a woman’s garden close to where the plane hit the ground in Parand.
There was also speculation over what caused “projectile holes” in the fuselage and a wing section of the aircraft.
Witnesses had heard loud explosions coming from a nearby military base before it was known that the Ukrainian International Airlines plane had crashed, according to locals’ claims on Twitter.
Bellingcat, an investigative website that did groundbreaking work on the July 2014 downing of a Malaysia Airlines flight over eastern Ukraine, cast doubts on the legitimacy of the photo and the claims that a charred piece of a rocket with a nose cone had been found in someone’s garden.
It tweeted: “The problem with this photo of the remains of an AA missile is it’s been taken at an angle where it’ll be next to impossible to geolocate, so unless another image appears which can be geolocated it won’t be possible to verify it’s in Iran.”
Ashkan Monfared, who posted the image on Twitter , where he described himself as an Iranian activist living in the US, wrote: “The photo was taken by an amateur who had no knowledge of the significance of the story and did not know what he had found. Hope to have more photos. I texted her and didn’t receive a reply yet.”
The crash site is less than two miles from an Iranian military base.
Footage recorded by a witness showed the plane in flames and glowing in the darkness as it fell from the sky.
British men Mohammed Reza Kadkhoda Zadeh, 40, who owned a dry cleaners in Brighton, BP engineer Sam Zokaei, 42, from south-west London, and PhD student and engineer Saeed Tahmasebi, who lived in Brentwood, Essex, died in the crash.
The Boeing 737-800 was en route to Kyiv and was carrying mostly Iranians and Iranian-Canadians.
It crashed while it was heading back to Tehran’s Imam Khomeini airport to make an emergency landing, said Iranian officials.
The airline said the plane was just three-years-old, had undergone scheduled maintenance two days before the disaster, and was being flown by an experienced crew.
Iranian officials said there was no radio communication from the pilot and the plane disappeared from radar at 8,000 ft.
Tehran referred to the crash as an accident just one day after the crash, but Ukraine is carrying out a criminal investigation ordered by the government.
It could take months to come to a conclusion.
Western security sources had told Reuters that there was evidence one of the engines had overheated and the initial assessment was the plane had suffered a technical malfunction and had not been brought down by a missile.
The crash happened hours after Iran launched missile attacks on US-led forces in Iraq, leading some to speculate that the plane may have been hit.
The Ukrainian investigators have been told to look for possible Russian missile parts in the debris field.
Kyiv’s experts in Iran include members of a team that probed the July 2014 downing of Malaysia Airlines flight MH17.
It was shot down over territory held by pro-Russian separatists in eastern Ukraine, killing all 298 on board.
Experts concluded it was hit by a Buk missile fired from a launcher smuggled into the country from Russia.