Iran will send the black box flight recorders from the passenger jet it accidentally shot down abroad for analysis, a senior investigator has said.

The recorders will first be sent to Ukraine, the plane’s home base, where French, Canadian and US experts will help examine them, the semi-official Tasnim news agency reported.

They are reportedly badly damaged, and could be sent on to France if the team in Kyiv are not able to read the flight data, Hassan Rezaeifer, head of accident investigations for Iran’s civil aviation department, was quoted as saying.

All 176 people on board the Ukraine International Airlines Boeing 737-800 were killed when the plane came down, with many of them being Iranian citizens or of Iranian heritage.

Tehran denied for several days that it had shot the plane down. The belated admission that its Revolutionary Guards were responsible has sparked protests across the country, from people angry about the deception as well as the deaths.

Iran had also initially insisted that it would not send the black boxes overseas for investigation, despite pressure from the Ukrainian authorities and the governments of other countries who lost citizens in the crash.

Fifty-seven of the dead were from Canada, and the country’s prime minister, Justin Trudeau, has been pushing hard for a full investigation. He said on Friday that France was one of a handful of countries with the technical expertise needed to extract information from the black boxes.

Other victims included 11 Ukrainians, 17 Swedish citizens, four Afghans and four British citizens. All countries are seeking a full investigation, and compensation to the families of the dead.

The shooting came hours after Iran targeted US airbases in Iraq with ballistic missiles, in retaliation for the killing of Gen Qassem Suleimani, Iran’s top commander and the most influential military figure in the Middle East.

Ayatollah Ali Khamenei gives a sermon before leading a Friday prayer for the first time in eight years in Tehran. Photograph: Anadolu Agency/Anadolu Agency via Getty Images

Iranian officials have blamed lower-level commanders for the “unforgivable mistake”, claiming they mistook the plane for a US missile fired in response to Iran’s earlier attacks.

The plane was designed and built in the US, and its engine by a joint US-French venture. Investigators from both countries have been invited to take part in the probe.

On Friday, Iran’s supreme leader, Ayatollah Ali Khamenei, delivered a rare sermon in Tehran in which he called the shooting down of the plane a “bitter tragedy that burned through our heart”.

But in an apparent response to Donald Trump’s expression of support for protesters, he described the US president as a “clown” who pretended to support the Iranian people but would push a poisonous dagger into their backs.

• This article was amended on 20 January 2020 because an earlier version incorrectly referred to Justin Trudeau as Canada’s president. He is that country’s prime minister.