NEW YORK, TEHRAN (AFP, IRNA) — A UN official on Tuesday accused Iran of lying in its explanation of how it shot down a Ukrainian passenger jet near Tehran last year at a time of acute tension with the U.S.

On January 8, 2020, Ukraine International Airlines flight PS752 crashed shortly after taking off from Iran’s capital Tehran killing all 176 people aboard, including 55 Canadians. The Islamic Republic admitted three days later that its forces mistakenly shot down the Kiev-bound Boeing 737-800 plane after firing two missiles.

Agnes Callamard, a special UN rapporteur on extra-judicial killings, unveiled the results of a probe into the tragedy and said the Iranian explanation of what went wrong is full of contradictions. UN experts like her are affiliated with the UN Security Council but this body is not bound by their conclusions.

“The most troubling thing is that the explanations by the Iranian authorities about the mistake or mistakes that were made do not add up”, Callamard told reporters. She stated the Iranian version of events is “full of contradictions. They are contradicted by the facts, by the technical assessments of many experts.”

“Why does Iran lie? Because there is no other term to use”, said Callamard. She cited what she said were Iranian statements about the “visual approach” of the aircraft and “instructions on the radar systems.”

Callamard said Iran has failed to explain how its military could make such a huge mistake as to shoot down a passenger plane. Callamard said that under international law it is possible to “kill by mistake” and that jurisprudence determines if the error was committed in good faith. “My conclusion is that on the basis of international law, error is not a defence for Iran”, said Callamard.

She said Iran had not answered the questions she asked as part of her investigation.

In reaction to the comments made by Agnes Callamard, Iranian Foreign Ministry spokesman Saeed Khatibzadeh said on Wednesday that she is not authorized to comment on the issue according to the mission of the Special Rapporteur on extrajudicial and arbitrary killings referred to in Resolution 44.5 of the Human Rights Council.