TEHERAN (BLOOMBERG) - A Ukrainian passenger plane that crashed after taking off from the Iranian capital on January 8 was downed by two short-range surface-to-air missiles, Iran's Civil Aviation Organisation said in a second preliminary investigation report.

The Tor-M1 missiles were launched at the Kyiv-bound Boeing 737-800 jetliner from the north, according to the report.

It also said the plane took off from Teheran at 6.12am local time and lost all contact with air traffic control at 8,100 feet.

Later, the aircraft disappeared from secondary surveillance radar screens at 6.15am and from primary surveillance radars at 6.18am.

The retrieved flight data recorder and the cockpit voice recorder are "some of the most advanced equipment of their kind in the world" and Iran lacks the facilities to decode them French and US accident investigation agencies have refused to send necessary equipment to Iran for decoding the black boxes.