The European Union on Friday demanded an "independent and credible" probe into the crash of a Ukrainian airliner in Iran which killed all 176 people on board.
Britain and Canada -- which lost 63 of its citizens in the disaster -- said there was intelligence to suggest that Iranian air defences mistakenly shot down the Ukraine International Airlines Boeing 737 with a missile. Tehran has denied the claim.
The EU said that, so far, there was "no conclusive evidence of what caused the incident", which killed 10 Swedes, three Germans and three Britons.
"It is very important for us that the investigation that takes place happens through an independent and credible civil safety investigation conducted in line with the International Civil Aviation Organisation rules," European Commission spokesman Stefan de Keersmaecker told reporters.
The EU is ready to give "any necessary assistance" to the probe, he added, but declined to answer directly when asked whether the bloc trusted Iran to carry out an independent investigation.
The disaster unfolded just hours after Tehran launched ballistic missiles towards bases in Iraq housing US troops in retaliation for the January 3 US drone strike in Baghdad that killed a top Iranian general.