Iran said it will hand over the black box flight recorders from the Ukrainian plane it shot down.
Hassan Rezaeifer, the head of accident investigations for the civil aviation department, said it was not possible to read the black boxes in Iran.
He said French, American and Canadian experts would try to analyse the recorders in Kyiv. If that does not work, the box will then be sent to France.
Iran shot down the plane shortly after it took off from Tehran on January 8, killing all 176 people on board.
Hours earlier, Iran launched a missile attack on two US bases in Iraq in response to America's killing of Iran’s top commander, General Qassem Soleimani.
Iranian officials said the lower-level officers believed the plane was a US cruise missile.
They had claimed the crash was caused by technical problems but later backtracked and admitted responsibility.
Western leaders heaped pressure on Iran, saying they had strong evidence the plane was hit by a surface-to-air missile.
The victims included 57 Canadian citizens as well as 11 Ukrainians, 17 people from Sweden, four Afghans and four British citizens. Most of those killed were Iranians.
The other five nations have called for Iran to accept full responsibility and pay compensation to the victims’ families.
The plane was a Boeing 737-800 that was designed and built in the US.
The plane’s engine was designed by CFM International, a joint company comprising the French group Safran and US group GE Aviation.
Investigators from both countries have been invited to take part in the probe.