A solemn ceremony was held at Tehran's largest cemetery on Friday to mark the second anniversary of the downing of a Ukrainian airliner, which killed 176 people, Anadolu News Agency reports.
Speaking at the ceremony, which was attended by senior civilian and military officials, as well as families of the victims, Amir Hossein Ghazizadeh, who heads Iran's Foundation of Martyrs and Veterans, called it "one of the saddest days" in the country's history.
He expressed hope that investigations into the incident would be finished soon and the perpetrators would be identified, echoing calls made by families of the victims.
The incident, which sent shockwaves across the world, came four days after Iran's top military Commander, Gen. Qassem Soleimani, was killed in a US drone strike on 3 January 2020 in Baghdad.
Two missiles struck a Ukrainian commercial flight after it had taken off from Tehran Airport, killing all people on board.
Iran called it a "human error," but countries such as Canada, the UK, Ukraine and Sweden, whose citizens were killed in the incident, have repeatedly rejected Iran's explanation.
In a statement, Iran's Foreign Ministry said it was ready to hold talks with the countries concerned, provided the talks respect "sovereignty (of countries), domestic laws and international obligations".
It said a criminal investigation has been held into the case and the Iranian Cabinet on 21 January 2021 agreed to pay $150,000 in reparations to each of the victims.
The statement came after Canada, Britain, Sweden, and Ukraine earlier this week said they had given up efforts to talk to Tehran about reparations and would resolve the matter in accordance with international law.
Meanwhile, many Iranians took to social media to pay tribute to the victims of the plane crash.
Javad Zarif, who served as Iran's Foreign Minister when the incident happened in early 2020, offered his "sincere condolences and apologies" to the families of victims.