Iran promises response to Ukraine plane crash 'ambiguities'
The Islamic republic admitted three days later that its forces mistakenly shot down the Kiev-bound Boeing 737-800 plane after firing two missiles.
But Agnes Callamard, a special UN rapporteur on extra-judicial killings, on Tuesday said the Iranian explanation of what went wrong is full of contradictions and amounted to lies.
Iran "has prepared detailed responses to the questions and ambiguities raised which will be handed over" before March 20, foreign ministry spokesman Saeed Khatibzadeh said in a statement on Wednesday.
The UN expert had relied on "erroneous, biased and non-pertinent information," he added.
He also criticised Callamard for getting involved in a topic that "has nothing to do with her mission or competence".
Callamard had told reporters the Iranian version of events was "contradicted by the facts, by the technical assessments of many experts."
"Why does Iran lie? Because there is no other term to use," she alleged.
Iran's civil aviation authority has said that poor tuning of an anti-aircraft unit's radar was the main human error behind the tragedy.
Tensions between Iran and the US were soaring at the time of the downing of the Ukrainian jetliner.
Iranian air defences were on high alert for a US counter-attack after Tehran fired missiles at a military base in Iraq that was used by US forces.
Those missiles were fired in response to the killing of General Qasem Soleimani, who headed the foreign operations arm of Iran's Islamic Revolutionary Guard Corps, in a US drone strike near Baghdad's international airport.
Iran said in December that it would pay $150,000 in compensation to each family that lost a loved one in the crash, a move heavily criticised by Ukraine, which has demanded the investigation finish first.
"We urgently call on Iran to provide a complete and thorough explanation of the events and decisions that led to this appalling plane crash," the coordination and response group made up of Canada, Britain, Ukraine, Sweden and Afghanistan said in a statement.
They also said they "will hold Iran to account to deliver justice and make sure Iran makes full reparations to the families of the victims and affected countries.”
Read also: A year on, questions haunt Iran's downing of Ukrainian plane
Meanwhile, Canada has rejected Iran’s compensation offer, saying: "The issue of compensation will not be set through unilateral statements by Iran but rather be subject to state-to-state negotiations.”
In mid-December, Canada's special counsel into the tragedy, former minister Ralph Goodale, issued a 70-page report arguing that Iran should not be "investigating itself" over the matter, emphasising that many of the key details surrounding the crash remained unknown.
Agencies contributed to this report.