Relatives of victims who died in the downing of the Ukrainian civilian airliner flight PS752 by Iranian missiles in January have claimed their loved ones' possession were "looted".

In a press conference held online on Tuesday, 160 days after the tragedy, Hamed Esmaeilion, who lost his wife and nine-year-old daughter in the crash, said: "Our families' belongings were looted, and what was not looted was confiscated by Iranian officials. No one knows where my wife's wedding ring and my daughter's pink doll is; they have not been returned," MiddleEastMonitor reported.

Esmaeilion said he lost his daughter's wristband, coat, carry on and both her Canadian and Iranian passports in the aftermath.

Other families also lost possessions including laptops, mobile phones, according to Esmaeilion.

"We have photos of Iranian officials just searching the bags and the luggage to find something. We do not know what they were doing," he said.

Tackling how the possessions were lost, the Iranian-Canadian told the conference the crash site was razed with bulldozers, burnt and destroyed after the Ukrainian airliner was downed, before an investigation could take place.

The Ukraine International Airlines flight PS752 was downed by missiles fired the Iranian Islamic Revolutionary Guard Corps (IRGC) on January 8, killing all 176 onboard.

Read alsoPS752 downing: Ukraine releases intercepted tower communications proving Iran was aware of missile launch all along

Iranian officials initially denied responsibility and insisted the plane crashed as a result of a technical fault. Days later, however, the Iranian military admitted it had shot down the plane, allegedly mistaking it for an incoming cruise missile.

Victims' relatives speaking at the press conference also raised other unanswered questions, including why Iranian officials have failed to hand over the black boxes to investigators and have now claimed the boxes are damaged, despite initially stating they were intact.

After "160 sleepless nights", families and supporters of the PS752 victims are demanding a plan for holding Iran to account.