FILE PHOTO: Rescue team works among debris of a plane belonging to Ukraine International Airlines, that crashed after take-off from Iran's Imam Khomeini airport, on the outskirts of Tehran, Iran January 8, 2020. Nazanin Tabatabaee/WANA (West Asia News Agency) via REUTERS

DUBAI (Reuters) - A Ukrainian airliner that crashed shortly after take-off from Tehran on Wednesday, killing all 176 people on board, was on fire immediately prior to the incident, according to an initial report by investigators.

The report, by Iran’s civil aviation organisation, cited witnesses on the ground and in a passing aircraft flying at high altitude as saying the jet was on fire while still aloft.