The 2020 downing of a Ukrainian airliner by Iran's Revolutionary Guards was the responsibility of high-level Iranian officials, not an accident caused by a missile system operator as Tehran claimed, families of victims have alleged.
The report by an association composed of mostly Canadian families of Flight PS752 victims challenges Iran's official findings that blamed a misaligned radar and an error by the air defence operator for downing the plane shortly after it took off from Tehran's Airport.
All 176 people on board were killed.
Iran's civil aviation body, which had responsibility for investigating the crash, said the operator mistook the jet for a missile at a time when tensions were high between Tehran and the United States.
A Canadian investigation in June condemned "those responsible" but found no evidence the tragedy was premeditated.
"It is the belief of the association that high-ranking officials of Iran are responsible for the downing of Flight PS752 and not just a handful of low ranking ... members as per the claims of the government of Iran," the association report said.
"At the highest levels of military alertness, the government of Iran used passenger flights as human shields against possible American attacks, by deliberately not closing the airspace to civilian flights," it said.
Association president Hamed Esmaeilion told a virtual news conference, "We think that the downing of PS752 was a deliberate act".
The Iranian foreign ministry was not immediately available to comment.
The association said it based its report on public information and recordings of "high-ranking Iranian officials" among its sources and was prepared with assistance from aviation and legal experts.
The report said the missile system operator was experienced, and should have been able to distinguish the airliner from a cruise missile.
A Canadian government spokeswoman said the country is analysing the report, which calls for an international investigation.
Many of the victims killed in the crash were Canadian citizens or permanent residents.
Canadian Foreign Affairs Minister Melanie Joly tweeted on Tuesday that the country "stands with Ukraine" in its decision to not take part in PS752 hearings at a military court in Iran, calling for "transparency in the criminal proceedings".
A group representing ministers from Canada, Sweden, Ukraine and the United Kingdom on Wednesday urged Iran in a statement to make "full reparations" for downing the jet, noting Tehran had not accepted recent requests to meet and negotiate.