Iran rejects claims it mistakenly shot down crashed Ukranian plane

Ali Abedzadeh, head of Iran's civil aviation department, has rejected claims that Tehran unintentionally hit the airliner with a surface-to-air missile, saying that such an eventuality was very unlikely given the close coordination between Iran's air defence and civil aviation department.

"As I said, based on the law, there is full coordination between our air defence and our civil system. Our civil aviation personnel and air defence personnel sit side by side, so it is absolutely impossible for such a thing to happen," Abedzadeh told a news conference.

Canadian Prime Minister Justin Trudeau also said his intelligence services have evidence an Iranian surface-to-air missile was responsible.

The plane came down after Iran launched missiles at military bases in Iraq where US forces were stationed. Video posted by the New York Times newspaper also appears to show the moment a missile hit the plane near Tehran's airport.

A CBS report citing US officials said the Ukrainian International Airlines Boeing 737-800 was hit by a missile.

CBS News quoted US intelligence sources as saying a satellite detected infrared "blips" of two missile launches, followed by another blip of an explosion.

Iranian officials have refused to hand over the plane's black box recorder over to Boeing and says it will conduct an internal investigation.

Iranian state television showed footage purportedly of the two black boxes recovered from the crashed Ukrainian airliner.

Both black boxes are damaged but their memory can be downloaded and examined, the commentary said.

Tehran says the allegations against them are "psychological warfare" as US-Iran ties remain fraught. It has also invited Ukraine to join the investigation.

Ukraine earlier said it was examining whether a missile strike brought down the aircraft - but Iran ruled this out.

The crash came just hours after Iran carried out missile strikes on two airbases housing US forces in Iraq.

German airline Lufthansa, meanwhile, said its flight from Frankfurt to Tehran was cancelled "as a precautionary measure" because of the security situation for airspace around the Iranian airport.

"As soon as we have detailed information, we will decide if and when our Iranian flights can be operated again," Lufthansa said in a statement.

Russian lawmakers say statements about a missile hitting the jetliner are "groundless" and they accuse the West of prematurely assigning blame to Tehran.

Vladimir Dzhabarov, a lawmaker with Russia's upper house of parliament, said Friday that "we need to be cautious with conclusions. Iranians have invited Ukraine to take part in the investigation. Why would they do it if they knew they had shot [the plane] down?"