US officials believe Iran accidentally shot down a Ukrainian airliner, killing all of the 176 people on board, US media reported Thursday.

Newsweek, CBS and CNN quoted unnamed officials saying they were increasingly confident that Iranian air defense systems accidentally downed the aircraft, based on satellite, radar and electronic data.

US officials believe Iran accidentally shot down a Ukrainian airliner, killing all of the 176 people on board, US media reported Thursday.

Newsweek, CBS and CNN quoted unnamed officials saying they were increasingly confident that Iranian air defense systems accidentally downed the aircraft, based on satellite, radar and electronic data.

Newsweek reported that several sources had informed it that the Ukrainian Airlines passenger jet that went down in Iran on Wednesday had been hit by a Russian-built surface-to-air missile.

Iran ruled out a missile strike, saying such a scenario made “no sense.”

“Several internal and international flights were flying at the same time in Iranian airspace at the same altitude of 8,000 feet (2,440 metres),” Iran’s transport ministry said. “This story of a missile striking a plane cannot be correct at all.”

“Such rumors make no sense,” Ali Abedzadeh, head of Iran’s civil aviation organization and deputy transport minister, said in the statement.

He said Iran and Ukraine were in the process of “downloading information” from black boxes retrieved from the crash site. “But if more specialized work is required to extract and analyse the data, we can do it in France or another country,” he added.

US President Donald Trump said he had “suspicions” about the crash.

“It was flying in a pretty rough neighborhood and somebody could have made a mistake,” he said.

“Some people say it was mechanical. I personally don’t think that’s even a question,” Trump said, adding that “something very terrible happened.”

According to the unnamed sources quoted by Newsweek, who were identified as US and Iraqi intelligence officials and a Pentagon official, Ukraine International Airlines flight 752 from Tehran to Kyiv was accidentally struck by a Tor-M1 shortly after takeoff.

The crash came immediately after Iran launched a ballistic missile attack against Iraqi military bases housing US troops amid a confrontation with Washington over its killing of an Iranian Revolutionary Guard general in a drone strike last week.

The plane was carrying 167 passengers and nine crew members from several countries, including 82 Iranians, at least 63 Canadians and 11 Ukrainians, according to officials. The crash just before dawn scattered flaming debris and passengers’ belongings across a wide stretch of farmland.

Eyewitnesses, including the crew of another passing flight, described seeing the plane engulfed in flames before crashing, the report said. The crash caused a massive explosion when the plane hit the ground, likely because the aircraft had been fully loaded with fuel for the flight to Kyiv, Ukraine.

Oleksiy Danilov, secretary of Ukraine’s Security Council, initially told Ukrainian media that officials had several working theories regarding the crash, including a missile strike.

“A strike by a missile, possibly a Tor missile system, is among the main [theories], as information has surfaced on the internet about elements of a missile being found near the site of the crash,” Danilov said.

He later told AFP that for the moment there was no reason to believe that the airliner had been hit by a missile.

An investigation team from Bellingcat, a journalism website that focuses on fact-finding, tweeted that it had seen an image purported to be Russian missile debris, but the angle of the picture meant it would be impossible to geolocate and prove it was at the crash site of the jetliner near Tehran.

Ukrainian investigators who arrived in Iran earlier on Thursday were awaiting permission from Iranian authorities to examine the crash site and look for missile fragments, Danilov said.

The Tor is a Russian-made missile system. Russia delivered 29 Tor-M1s to Iran in 2007 as part of a $700 million contract signed in December 2005. Iran has displayed the missiles in military parades.

Investigators have previously blamed Russian missiles on the 2014 crash of a Malaysia Airlines that crashed in Ukraine as it returned home from Amsterdam, killing 298 people including 193 Dutch nationals.

Reuters had previously reported that Western intelligence agencies believed that the plane suffered a technical malfunction and was not shot down.

The wire service quoted five unnamed security sources — three American, one European and one Canadian — as saying the initial assessment was that Tehran’s explanation was accurate. The Canadian source was quoted as saying there was evidence one of the aircraft’s engines had overheated.

Qassem Biniaz, a spokesman for Iran’s Road and Transportation Ministry, said it appeared a fire erupted in one of its engines and the pilot lost control of the plane, according to the state-run IRNA news agency. The news report did not explain how Iranian authorities knew that.

British Prime Minister Boris Johnson called Thursday for a “full, credible and transparent” investigation into the crash.

A spokesman said reports about what happened were “very concerning.”

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

“The prime minister said that there needed to be a full, credible and transparent investigation into what happened,” the spokesman said.

He added: “The reports we have seen are very concerning and we are urgently looking into them.”

In Kyiv, the Ukrainian presidency said Zelensky invited Britain to join the probe, and also called for a “transparent, thorough and objective investigation that can quickly establish the facts of this tragedy.”

Ottawa also called Thursday for its own experts be allowed to join the investigation into the crash.

In a rare phone call with his Iranian counterpart Javad Zarif late Wednesday, Canada’s Foreign Minister Francois-Philippe Champagne called for Iran to allow Canadian investigators in to the country, the Canadian foreign ministry said in a statement.

“Minister Champagne stressed the need for Canadian officials to be quickly granted access to Iran to provide consular services, help with identification of the deceased and take part in the investigation of the crash,” the statement said.

Iran is refusing to hand over for analysis the black boxes from the plane, Iranian media reported Wednesday.

But Zelensky said Iranian President Hassan Rouhani had assured him of full cooperation in investigating the fatal crash and that Iran would provide experts access to all data.