Authorities have found both flight recorders from the plane that crashed on Saturday in western Russia, killing Poland's president, Emergency Minister Sergei Shoigu said.
"Both the data and the voice recorders were found at the crash site. The analysis of them, which will shed light on the reasons for the disaster, has already begun," Shoigu was quoted as saying by Interfax news agency.
Such recorders are often called "black boxes" and are used to reconstruct the chain of events that led to a crash.
Officials have said a total of 96 people were aboard the plane, including Polish President Lech Kaczynski and other top officials from his country.
All of them are believed to be dead.