Iran has confirmed two missiles were fired at a Ukrainian airliner brought down this month, in a catastrophic error that killed all 176 people on board and sparked angry protests.

The country’s civil aviation authority said it has yet to receive a positive response after requesting technical assistance from France and the United States to decode black boxes from the downed airliner.

The Kiev-bound Ukraine International Airlines plane was accidentally shot down shortly after takeoff from Tehran’s Imam Khomeini International Airport on January 8.

Iran has come under mounting international pressure to carry out a full and transparent investigation into the air disaster.

“Investigators… discovered that two Tor-M1 missiles… were fired at the aircraft,” Iran’s Civil Aviation Organisation said in a preliminary report posted on its website late Monday.

It said an investigation was ongoing to assess the bearing their impact had on the accident.

The statement confirms a report in The New York Times which included video footage appearing to show two projectiles being fired at the airliner.

The Tor-M1 is a short-range surface-to-air missile developed by the former Soviet Union that is designed to target aircraft or cruise missiles.

Iran had for days denied Western claims based on US intelligence reports that the Boeing 737 operating Flight PS752 had been shot down.

It came clean on January 11, with the Revolutionary Guards’ aerospace commander Brigadier General Amirali Hajizadeh accepting full responsibility.

But he said the missile operator who opened fire had been acting independently.