FILE PHOTO: Security officers and Red Crescent workers are seen at the site where the Ukraine International Airlines plane 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) - An Iranian official said on Friday it could take “one or two years” to complete the investigation into the crash of a Ukrainian airliner outside Tehran with the loss of all 176 on board.

The official also said it could take one or two months to download the black boxes recovered from the crash site.

State TV earlier showed footage of the black boxes purportedly at the Iran Civil Aviation Organisation.

Iran prefers to download the black box data but could send it to Russia, Canada, France or Ukraine if needed as Tehran has agreements with those countries, the official said.