Aviation officials in Moscow say there were non-crew members in the cockpit of a plane which crashed in poor weather last month, killing the Polish President Lech Kaczynski and more than 90 other people.
The officials say that shortly before the crash, three voices belonging to people who were not members of the crew were recorded inside the cockpit.
One has been identified, but the person's name has not been released.
The plane came down in poor weather near the Russian city of Smolensk.
The initial results of the investigation into the crash have ruled out an explosion or a fire on board and show there was no mechanical failure involved.