Iran has rejected reports it will send the black boxes from downed Ukrainian International Airlines flight 752 abroad for analysis after the plane was accidentally shot down by the military.

The official leading the investigation into the crash which killed all 176 people on board appeared to backtrack on his own statement 24 hours earlier which said that the data recorders would be read in Ukraine.

“We are trying to read the black boxes here in Iran,” Hassan Rezaifar, a director at Iran’s Civil Aviation Organisation, told state news agency IRNA on Sunday.

“Otherwise, our options are Ukraine and France, but no decision has been taken so far to send them to another country.”

Mr Rezaifar had previously been quoted by Iran’s semi-official Tasnim news agency on Saturday as saying the black boxes could not be decoded in Iran and would be read in Ukraine with the help of experts from France, Canada and the US.

Iran plane crash: Tehran admits accidentally shooting Boeing 737 Show all 25 1 /25 Iran plane crash: Tehran admits accidentally shooting Boeing 737 Iran plane crash: Tehran admits accidentally shooting Boeing 737 People standing and analysing the fragments and remains of the Ukraine International Airlines plane Boeing 737-800 that crashed outside the Iranian capital Tehran on January 8 National Security and Defense Council of Ukraine/AFP Iran plane crash: Tehran admits accidentally shooting Boeing 737 A hole in a part of Ukraine International Airlines Flight PS752 Iran said on January 11, it "unintentionally" shot down a Ukrainian passenger jet, killing all 176 people aboard, in an abrupt about-turn after initially denying Western claims it was struck by a missile Ukrainian Presidential Press Service/EPA Iran plane crash: Tehran admits accidentally shooting Boeing 737 Tehran Iranians protested in front of the Amir Kabir University in Tehran after the Iranian military released their statement about the flight EPA Iran plane crash: Tehran admits accidentally shooting Boeing 737 Debris of the wreckage Iranian president said a military probe into the tragedy had found "missiles fired due to human error" brought down the Boeing 737, calling it an "unforgivable mistake" National Security and Defense Council of Ukraine/AFP Iran plane crash: Tehran admits accidentally shooting Boeing 737 Tehran Local newspapers in Tehran carrying headlines such as: "National Mourning", "Apologize, Resign", "Unforgivable", "Great Disaster" ... concerning the downed Ukranian jetliner AFP via Getty Iran plane crash: Tehran admits accidentally shooting Boeing 737 Kiev, Ukraine Ukraine International Airlines President Yevhenii Dykhne stands next to a map of flight PS-752's departure path at a news briefing about the crash Reuters Iran plane crash: Tehran admits accidentally shooting Boeing 737 Tehran The Iranian students demonstrated following a tribute for the victims AFP via Getty Iran plane crash: Tehran admits accidentally shooting Boeing 737 The Canadian passport of a victim This handout photograph taken and released on January 11, 2019, by The National Security and Defense Council of Ukraine, shows the Canadian passport of avictim of the Ukraine International Airlines plane Boeing 737-800 that crashed outside the Iranian capital Tehran on January 8, 2020. - Iran said on January 11, 2020 it "unintentionally" shot down a Ukrainian passenger jet, killing all 176 people aboard, in an abrupt about-turn after initially denying Western claims it was struck by a missile. Iranian president said a military probe into the tragedy had found "missiles fired due to human error" brought down the Boeing 737, calling it an "unforgivable mistake". (Photo by STR / National Security and Defense Council of Ukraine / AFP) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / National Security and Defense Council of Ukraine" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS (Photo by STR/National Security and Defense Co/AFP via Getty Images) STR National Security and Defense Council of Ukraine/AFP Iran plane crash: Tehran admits accidentally shooting Boeing 737 This combination of satellite pictures shows a before and after image of the crash site in Tehran The image (top), according to Maxar, shows vehicles and personnel (centre) during accident recovery and investigation on January 11, with a wall by the soccer pitch (left) destroyed as well as a wall (top right). The image below was taken on November 27, 2019 Maxar Technologies/AFP Iran plane crash: Tehran admits accidentally shooting Boeing 737 Ukraine The portraits of victims with flowers and candles at Boryspil International Airport in Kiev EPA Iran plane crash: Tehran admits accidentally shooting Boeing 737 Holes in the wreckage This handout photograph taken and released on January 11, 2019, by The National Security and Defense Council of Ukraine, shows holes in the wreckage of the Ukraine International Airlines plane Boeing 737-800 that crashed outside the Iranian capital Tehran on January 8, 2020. - Iran said on January 11, 2020 it "unintentionally" shot down a Ukrainian passenger jet, killing all 176 people aboard, in an abrupt about-turn after initially denying Western claims it was struck by a missile. Iranian president said a military probe into the tragedy had found "missiles fired due to human error" brought down the Boeing 737, calling it an "unforgivable mistake". (Photo by STR / National Security and Defense Council of Ukraine / AFP) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / National Security and Defense Council of Ukraine" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS (Photo by STR/National Security and Defense Co/AFP via Getty Images) STR National Security and Defense Council of Ukraine/AFP Iran plane crash: Tehran admits accidentally shooting Boeing 737 Tehran People gathered for a candlelight vigil at the gate of Amri Kabir University AP Iran plane crash: Tehran admits accidentally shooting Boeing 737 People standing and analysing the fragments and remains of the Ukraine International Airlines plane This handout photograph taken and released on January 11, 2019, by The National Security and Defense Council of Ukraine, shows people standing and analysing the fragments and remains of the Ukraine International Airlines plane Boeing 737-800 that crashed outside the Iranian capital Tehran on January 8, 2020. - Iran said on January 11, 2020 it "unintentionally" shot down a Ukrainian passenger jet, killing all 176 people aboard, in an abrupt about-turn after initially denying Western claims it was struck by a missile. Iranian president said a military probe into the tragedy had found "missiles fired due to human error" brought down the Boeing 737, calling it an "unforgivable mistake". (Photo by STR / National Security and Defense Council of Ukraine / AFP) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / National Security and Defense Council of Ukraine" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS (Photo by STR/National Security and Defense Co/AFP via Getty Images) STR National Security and Defense Council of Ukraine/AFP Iran plane crash: Tehran admits accidentally shooting Boeing 737 Protests against war with Iran took place in London The demonstration was co-organized by the Campaign For Nuclear Disarmament and the Stop the War Coalition, an activist group formed in 2001 Getty Iran plane crash: Tehran admits accidentally shooting Boeing 737 A hole in a part of Ukraine International Airlines Flight epa08119576 An undated handout picture provided by the Ukrainian Presidential Press Service allegedly shows a hole in a part of Ukraine International Airlines Flight PS752, issued on 11 January 2020. According to media reports on 11 January 2020, the Iranian military released a statement claiming that Ukraine International Airlines flight PS752 was shot down due to 'human error.' The Ukrainian jet, flying from Tehran, Iran, to Kiev, Ukraine, crashed minutes after takeoff on 08 January 2020, killing all 167 passengers and nine crew members aboard. EPA/UKRAINE PRESIDENTIAL PRESS SERVICE HANDOUT BEST QUALITY AVAILABLE HANDOUT EDITORIAL USE ONLY/NO SALES UKRAINE PRESIDENTIAL PRESS SERVICE HANDOUT Ukrainian Presidential Press Service/EPA Iran plane crash: Tehran admits accidentally shooting Boeing 737 Labour Party leader spoke at the event Jeremy Corbyn posing with an anti-war banner during the demonstration against the threat of war on Iran, in Trafalgar Square AFP via Getty Images Iran plane crash: Tehran admits accidentally shooting Boeing 737 A rose rests on a page featuring photographs of people who died in Iran Iranian Americans from across California converged in Los Angeles to participate in the California Convention for a Free Iran Reuters Iran plane crash: Tehran admits accidentally shooting Boeing 737 A young boy protests against a possible war with Iran in London A young protester at a Campaign for Nuclear Disarmament demonstration against a possible war with Iran in Trafalgar Square, central London. PA Photo. Picture date: Saturday January 11, 2020. See PA story POLITICS Iran. Photo credit should read: Jonathan Brady/PA Wire Jonathan Brady PA Iran plane crash: Tehran admits accidentally shooting Boeing 737 Holes in the wreckage This handout photograph taken and released on January 11, 2019, by The National Security and Defense Council of Ukraine, shows holes in the wreckage of the Ukraine International Airlines plane Boeing 737-800 that crashed outside the Iranian capital Tehran on January 8, 2020. - Iran said on January 11, 2020 it "unintentionally" shot down a Ukrainian passenger jet, killing all 176 people aboard, in an abrupt about-turn after initially denying Western claims it was struck by a missile. Iranian president said a military probe into the tragedy had found "missiles fired due to human error" brought down the Boeing 737, calling it an "unforgivable mistake". (Photo by STR / National Security and Defense Council of Ukraine / AFP) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / National Security and Defense Council of Ukraine" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS (Photo by STR/National Security and Defense Co/AFP via Getty Images) STR National Security and Defense Council of Ukraine/AFP Iran plane crash: Tehran admits accidentally shooting Boeing 737 Rescue workers search the scene on January 8 In this Wednesday, Jan. 8, 2020, photo, rescue workers search the scene where a Ukrainian plane crashed in Shahedshahr, southwest of the capital Tehran, Iran. Iran on Saturday, Jan. 11, acknowledged that its armed forces "unintentionally" shot down the Ukrainian jetliner that crashed earlier this week, killing all 176 aboard, after the government had repeatedly denied Western accusations that it was responsible. (AP Photo/Ebrahim Noroozi) Ebrahim Noroozi AP Iran plane crash: Tehran admits accidentally shooting Boeing 737 Rescue workers search the scene In this Wednesday, Jan. 8, 2020 photo, rescue workers search the scene where a Ukrainian plane crashed in Shahedshahr, southwest of the capital Tehran, Iran. Iran on Saturday acknowledged that its armed forces "unintentionally" shot down the Ukrainian jetliner that crashed earlier this week, killing all 176 aboard, after the government had repeatedly denied Western accusations that it was responsible. (AP Photo/Ebrahim Noroozi) Ebrahim Noroozi AP Iran plane crash: Tehran admits accidentally shooting Boeing 737 Debris of the Ukraine International Airlines General view of the debris of the Ukraine International Airlines, flight PS752, Boeing 737-800 plane that crashed after take-off from Iran's Imam Khomeini airport, on the outskirts of Tehran, Iran January 8, 2020 is seen in this screen grab obtained from a social media video via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. MANDATORY CREDIT. SOCIAL MEDIA Reuters Iran plane crash: Tehran admits accidentally shooting Boeing 737 Debris of the Ukraine International Airlines (FILES) In this file photo taken on January 8, 2020 rescue teams are seen at the scene of a Ukrainian airliner that crashed shortly after take-off near Imam Khomeini airport in the Iranian capital Tehran. - Iran said on January 11 that it unintentionally shot down the Ukrainian plane due to 'human error'. (Photo by Akbar TAVAKOLI / IRNA / AFP) (Photo by AKBAR TAVAKOLI/IRNA/AFP via Getty Images) AKBAR TAVAKOLI IRNA/AFP/Getty Iran plane crash: Tehran admits accidentally shooting Boeing 737 One of the engines of the plane lies among the wreckage epa08118590 (FILE) - One of the engines of the plane lies among the wreckage after a Ukraine International Airlines Boeing 737-800 carrying 176 people crashed near Imam Khomeini Airport in Tehran, killing everyone on board, in Shahriar, Iran, 08 January 2020 (reissued 11 January 2020). According to media reports, the Iranian military released a statement on 11 January claiming that Ukraine International Airlines flight 752 was shot down due to a human error. EPA/ABEDIN TAHERKENAREH ABEDIN TAHERKENAREH EPA Iran plane crash: Tehran admits accidentally shooting Boeing 737 Debris of the Ukraine International Airlines FILE - In this Jan. 8, 2020, photo, debris is seen from an Ukrainian plane which crashed as authorities work at the scene in Shahedshahr, southwest of the capital Tehran, Iran. Iran announced Saturday, Jan. 11, that its military â€œunintentionallyâ€ shot down the Ukrainian jetliner that crashed earlier this week, killing all 176 aboard, after the government had repeatedly denied Western accusations that it was responsible. (AP Photo/Ebrahim Noroozi, File) Ebrahim Noroozi AP

Canada, which had 57 citizens on the Boeing 737-800, has called for the black boxes to be sent to France for analysis. Two investigators from the country’s transportation safety board (TSB) examined the wreckage during a six-day visit before leaving Tehran on Sunday.

“There are still no firm plans as to when and where the aircraft recorders will be downloaded and analysed,” the TSB said in a statement.

Canadian foreign minister Francois-Philippe Champagne said that he had written to his Iranian counterpart Mohammad Javad Zarif on Sunday to urge the boxes be quickly sent to Ukraine or France.

“The wish of the international community is that the black boxes be sent where they should be sent ... to ensure we have proper technical expertise when [they] are opened,” he added.

Meanwhile, the bodies of 11 Ukrainian victims were brought home on Sunday in a ceremony at Kiev airport. Ukrainian foreign minister Vadym Prystaiko said that “bereaved families and the whole nation have an opportunity to pay their respects”.

Flight 752 was en route from Tehran to the Ukrainian capital when it crashed on 8 January. After initially denying responsibility, Iran’s elite Revolutionary Guards admitted it accidentally brought down the plane after mistaking it for a US cruise missile attack.

The confession deepened the crisis gripping Iran as thousands of people took to the streets in several cities to demand the resignation of president Hassan Rouhani and to criticise supreme leader Ali Khamenei.