Russia on Friday invited foreign diplomats and experts to attend the examination of a flight recorder from a Russian warplane downed by Turkey last month.
Turkey shot down the Russian Su-24 bomber at the border with Syria on November 24 saying it violated its airspace for 17 seconds despite repeated warnings. Russia insists the plane never entered Turkish airspace.
The incident, in which one pilot and a Russian marine of the rescue party were killed, badly strained previously close ties between the two economic partners.
Lt. Gen. Sergei Dronov, a deputy commander of the Russian aerospace forces, told reporters on Friday that Moscow has invited experts from 14 countries to take part in the study of the plane's flight data recorder, which was recovered by Russian and Syrian forces from the area where the plane was shot down, but only British and Chinese experts have accepted the offer.
Dronov reaffirmed that the Su-24 hadn't violated Turkish airspace. Russian officials expect the recorder's data to definitively prove that assertion.
However, Lt.-Gen. Sergei Bainetov, a deputy head of the flight safety service of the Russian military, said after a preliminary inspection of the recorder that its data board had been damaged. It wasn't immediately clear what data might have been lost.
Russian television on Friday aired an hour-long live broadcast from the lab as Russian experts unsealed the recorder and removed the data board in the presence of foreign experts.
Dronov said the data from the recorder will be released on Monday.
President Vladimir Putin again denounced Turkey's action during his annual news conference, saying that it is now "practically impossible" to repair ties under the current Turkish leadership.