Non-crew members were in the cockpit of the Polish presidential plane that crashed in April near the western Russian city of Smolensk, killing everyone on board, the head of the Interstate Aviation Committee said on Wednesday.
"It was proven that non-crew members were in the cockpit," Tatyana Anodina said.
She said the voice of one person was identified while the others are being identified by Polish officials.
Anodina did not specify the number of people in the cockpit or their identities.
Polish president Lech Kaczynski died in the plane crash near the western Russian city of Smolensk April 10.
The president and first lady died along with 95 other people, including a high-ranking Polish delegation, also travelling on the plane.