KYIV, Jan 9 - The Ukrainian passenger plane that crashed shortly after taking off from Tehran’s international airport Wednesday was shot down by an Iranian anti-aircraft missile, Fox News reported Thursday citing Pentagon officials.

Officials said U.S. intelligence increasingly points at the airliner being accidentally struck by a Russian-made missile, killing all 176 people on board the flight, just hours after Iran fired more than a dozen ballistic missiles targeting two military bases housing American and coalition troops.

"An absolute tragedy," one U.S. official told Fox News. "They just screwed up and it is tragic."

The revelations come as Ukrainian investigators reportedly are awaiting permission from Iranian authorities to examine the crash site and look for missile fragments.

Iran's head of civil aviation was quoted by the ISNA News Agency as saying Thursday that "scientifically, it is impossible that a missile hit the Ukrainian plane, and such rumors are illogical," according to Reuters. Iranian officials have blamed a technical malfunction for the aircraft’s doom.

The U.S. official told Fox News that a Russian-made SA15 missile, which is part of the Tor surface-to-air missile system, was the kind that brought down the aircraft. Russia delivered 29 Tor-M1 systems to Iran in 2007 as part of a $700 million contract signed in December 2005. Iran has displayed the missiles in military parades as well.

"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," Oleksiy Danilov, secretary of Ukraine's Security Council, told Ukrainian media earlier.

When asked Thursday about what could have happened to the Ukrainian International Airlines flight, President Trump said he didn't believe that a mechanical failure caused the plane crash.

"It was flying in a pretty rough neighborhood," he said. "Somebody could have made a mistake on the other side."

Danilov also said other possible causes under consideration for Wednesday's downing included a drone or another flying object crashing into the plane, a terrorist attack or an engine malfunction causing an explosion.

The crash came just a few hours after Iran launched a ballistic missile attack against Iraqi military bases housing U.S. troops amid a confrontation with Washington over it killing an Iranian Revolutionary Guard general in a drone strike last week.

Gen. Abolfazl Shekarchi, the spokesman of the Iranian armed forces, earlier denied a missile hit the airplane in comments reported Wednesday by the Fars news agency. He dismissed the allegation as "psychological warfare" by foreign-based Iranian opposition groups. (fox/ez)