The UN aviation agency's governing body Friday called on Iran to speed up its investigation into a Kiev-bound passenger plane mistakenly shot down in January and issue a final report.

Ukraine International Airlines Flight 752 crashed shortly after taking off from the Iranian capital's main airport on January 8. 

The Islamic republic admitted days later that its forces accidentally shot down the plane, killing all 176 people on board, after firing two missiles amid heightened US-Iran tensions.

The International Civil Aviation Organization (ICAO) Council, backed by all 36 member states, issued a statement calling on Iran to "expedite the accident investigation."

"We have had several exchanges with the Iranian CAA (Civil Aviation Authority) in which we urged its authorities to expedite the accident investigation in accordance with ICAO Annex 13 provisions," ICAO Council President Salvatore Sciacchitano said.

Annex 13 outlines that final accident reports should be issued within 12 months of a crash.

Both Sciacchitano and Canadian Transport Minister Marc Garneau noted the "grief and expectations" of the families of Flight PS752 crash victims.

Canada, which lost 55 nationals and 30 permanent residents in the crash, has demanded answers from Iran after Tehran's "limited" initial report failed to explain why it fired missiles at the plane.

Iran's civil aviation authority has said the misalignment of an air defence unit's radar system was the key "human error" that led to the plane's downing.

Iran last month vowed to reveal "detailed" information on the probe by the end of October.