KYIV, Jan 8 – The initial assessment of Western intelligence agencies is that a Ukrainian airliner which crashed in Iran on Wednesday was not brought down by a missile, Reuters reported citing a Canadian security source.

The source, who declined to be identified, said the agencies believed the Boeing 737 plane had suffered a technical malfunction. The Ukraine International Airline jet crashed shortly after takeoff from Tehran, killing all 176 people on board.

The disaster occurred shortly after Iran launched a series of missile attacks against two military bases in Iraq that housed U.S. troops.

“The initial assessment of Western intelligence agencies is that the plane was not brought down by a missile. There is no evidence to suggest that,” said the source.

Ukraine has temporarily banned on flights to Iran, Prime Minister Oleksiy Honcharuk said at a briefing on Wednesday. "Until finding out the reasons for the tragedy, we have decided to suspend the operation of Ukrainian airlines in Iranian airspace. As soon as the reasons are clarified, the decision will be reviewed," he said.

Meanwhile, the western intelligence agencies believe the most likely cause of the crash was a malfunction, the source added, saying there was some evidence one of the plane’s engines had overheated.

Boeing said it had no additional comment. Earlier, the company said it was in contact with the airline and was ready to assist.

In July 2014 a Malaysia Airlines flight from Amsterdam to Kuala Lumpur was shot out of the sky over eastern Ukraine during a rebellion by Russian-backed separatists, killing all 298 people on board.

U.S. Secretary of State Mike Pompeo said on Wednesday the United States was calling for complete cooperation with any investigation into the cause of the crash of a Ukrainian airliner in Iran.

In a statement, Pompeo said the United States was prepared to offer Ukraine all possible assistance after the crash.

“The United States will continue to follow this incident closely and stands prepared to offer Ukraine all possible assistance. The United States calls for complete cooperation with any investigation into the cause of the crash.”

Under international rules, responsibility for investigating the crash lies with Iran, and Iranian state television said both of the plane’s black box voice and data recorders had been found. (rt/ez)