The black boxes of a Ukrainian passenger plane that Iranian forces mistakenly shot down in January have arrived in France, air investigators said on Saturday. A source at France's Bureau for Inquiry and Analysis for Civil Aviation Safety confirmed the boxes had arrived and that the agency would begin analysis. The comment came after an announcement by Iranian officials. "The black boxes were transferred to Paris yesterday by aviation organisation officials and a judge and their reading will start on Monday," Mohsen Baharvand, Iran's deputy foreign minister for international and legal affairs, was quoted as saying by the <em>Etemad</em> newspaper. "The French government has co-operated very well with the Iranian delegation and it is fitting that I thank them for this," he added. Iran admitted to accidentally shooting down the Boeing 737-800 in January, killing all 176 people aboard saying it was mistaking it for an incoming missile. Iranian armed forces had been bracing for a counterattack after launching missiles at US bases in Iraq in response to the killing of its Quds Force commander Gen Qassim Soleimani in a US strike earlier in January. The incident was condemned widely and Iran has engaged in intense negotiations with Ukraine, Canada and other nations that had citizens aboard the downed plane. The countries led the international campaign for a thorough, independent investigation into the incident after Iran attempted to keep the flight recorders to be studied in Tehran and also attempted to clear the crash site with heavy equipment. To analyse the boxes domestically, however, Iranian experts needed a converter to recover data but the US opposed providing it to Iran. Few labs around the world have the equipment needed to analyse the data held on the crushproof boxes but it is unclear why they were specifically sent to France. Initially, Tehran blamed the crash on technical problems and only acknowledged shooting down the plane days later as evidence came to light. Iran has since said that the misalignment of an air defence unit's radar system was the cause of the "human error" that led to the plane's downing. A 20-member international team will examine the boxes, which are expected to contain information about the last moments before the aircraft crashed. Canada, whose nationals made up most of the victims on board the jetliner, along with Ukraine, had demanded for months that Iran send the black boxes abroad so their contents can be analysed. With no means of decoding the recorders domestically, Iran had blamed the delay in sending them on the novel coronavirus pandemic, which has seen most international flights cancelled. US President Donald Trump reimposed sweeping sanctions on Iran after withdrawing the US from Tehran's nuclear deal with world powers over two years ago.