More than 170 people died after a Ukrainian Boeing-737 crashed in Iran on January 8.
Ukraine International Airlines flight PS752 to Kyiv, carrying 176 on board, went down after taking off from Imam Khomeini airport in Tehran at 06:12 local time.
According to officials, there is no chance of finding survivors.
The majority of passengers were from Iran and Canada.
The embassy of Ukraine in Tehran initially blamed engine failure but later removed the statement.
It said any comment regarding the cause of the accident prior to a commission’s inquiry was not official.
Ukraine’s President Volodymyr Zelensky warned against “speculation or unchecked theories regarding the catastrophe” until official reports were ready.
Iranian media blamed technical problems and quoted an aviation official who said no emergency had been declared.
In a sign of the potential difficulties facing crash investigators, Ali Abedzadeh, the head of Iran’s civil aviation organization was quoted as saying the Ukrainian plane’s black box would not be handed over, either to Boeing or the Americans.
Ali Abedzadeh said “terrorism” had played no role in the crash, Iran’s conservative Mehr news agency reported.
Debris and engine parts from the Boeing 737-800 NG plane were found some 6 miles from the airport and rescue workers with face masks searched the wreckage for victims.
Throughout the morning, Red Crescent workers laid out a long line of body bags.
Hours before the plane came down Iran carried out a ballistic missile attack on two air bases housing US forces in Iraq. However, there is no evidence that the two incidents were linked.
A series of airlines announced on January 8 that they were avoiding both Iranian and Iraqi airspace.
KLM and Air France said they would use alternative routes while Lufthansa said it was also canceling its daily flight to Tehran. Air India, Qantas, Singapore Airlines, Japan Airlines, and Malaysia Airlines were among other airlines taking action.
According to Ukrainian Foreign Minister Vadym Prystaiko, among the victims were 82 Iranians, 63 Canadians, 11 Ukrainians including all nine crew, 10 Swedes, four Afghans, three Britons and three Germans,
Ukrainian officials said that 169 people had bought tickets for the flight but two had not boarded the plane.