The announcement by the head of Iran’s Civil Aviation Organisation marks the first official report on the contents of the cockpit voice and data recordings, which were sent to France for reading in July.

Tehran has said it accidentally shot down the Ukraine airliner in January, at a time of extreme tensions with the US. All 176 people aboard the plane were killed.

“Nineteen seconds after the first missile hit the plane, the voices of pilots inside the cockpit, indicated that the passengers were alive … 25 seconds later the second missile hit the plane,” Touraj Dehghani-Zanganeh was cited as saying by state television.

Iran has been in talks with Ukraine, Canada and other nations that had citizens aboard the downed plane, and who have demanded a thorough investigation into the incident.

“The data analysis from the black boxes should not be politicised,” Zanganeh said.

Iran’s Revolutionary Guards shot down the Ukraine International Airlines flight with a ground-to-air missile on Jan 8, just after the plane took off from Tehran, in what Tehran later acknowledged as a “disastrous mistake” by forces on high alert during a confrontation with the US.

Iranian and Ukrainian officials have held talks on the compensation to families of the victims. Another round of talks is set for October.