The remains of the Ukrainian Boeing 737-800. Photo Tasnim News agency

The Ukraine Airlines flight which crashed in Tehran killing 176 people on Wednesday was shot down by an Iranian anti-aircraft missile system, Pentagon officials have said in a report by Newsweek.

Ukraine International Airlines Flight 752 was struck by a Russia-built Tor-M1 surface-to-air missile system, the magazine reported, quoting three security officials.

Two of the officials said the aircraft was likely targeted by mistake by Iranian missile system as Iran awaited a possible counter-strike after sending rockets to two US bases in Iraq.

The aircraft was a Boeing 737-800, bound for Kiev.

It came down in a blaze just three minutes after take off, crashing in the outskirts of Iranian capital.

Canadian officials said 138 of the 167 passengers took the plane to connect flights to Canada.

There were 63 Canadians, 82 Iranians, 10 Swedes, 3 Brits, 11 Ukrainians, four Afghans and 3 Germans and nine crew members aboard the plane.