An international investigation team has completed a preliminary analysis of data from the black boxes of a Ukrainian passenger plane mistakenly shot down by Iran in January, the Transportation Safety Board of Canada said Thursday.

"The download and preliminary data analysis was an important milestone in what must be a thorough and transparent safety investigation," said TSB chair Katy Fox, without providing details on the results of the analysis.

"The work in Paris is finished, but the investigation is far from over. There are still many key questions that need to be answered," she said in a statement.

"We have urged Iran to release factual information from the recorders as soon as possible," Fox said, adding that Iran -- which is leading the investigation -- has not authorized the TSB to release details.

A team of investigators from the same countries as the victims of the plane crash met this week at France's Bureau for Enquiry and Analysis for Civil Aviation Safety (BEA), in Paris, to begin extracting the data.

On Monday, the BEA announced data from the black boxes had been successfully downloaded.

This photograph taken and released on January 11, 2020 by The National Security and Defense Council of Ukraine shows people analyzing the wreckage from the Ukraine International Airlines plane that crashed outside the Iranian capital Tehran
This photograph taken and released on January 11, 2020 by The National Security and Defense Council of Ukraine shows people analyzing the wreckage from the Ukraine International Airlines plane that crashed outside the Iranian capital Tehran National Security and Defense Council of Ukraine / STR

The data included details from the cockpit voice recorder, which records conversations between the pilots and noises on the plane, as well as the flight data recorder, which tracks the flight parameters.

The data was handed over to the Iranian investigation bureau. The bureau is leading the investigation, and the BEA acts as the technical service provider.

Ukraine International Airlines flight 752 was struck by two missiles and crashed shortly after taking off from Tehran's main airport on January 8.

The Islamic republic admitted days later that its forces accidentally shot down the Kiev-bound jetliner, killing all 176 people on board.

The majority of the victims were Iranian or Canadian, and many were dual nationals.

Canada had demanded for months along with Ukraine that Iran send the black boxes abroad so their contents could be analyzed.

The BEA announced at the end of June that Iran had officially requested its technical assistance in repairing and downloading the data from the black boxes.

Ukraine Canada