Russian and Polish experts were checking the flight recorders of the crashed plane, which killed Polish President Lech Kaczynski and 95 others on board on Saturday, Russian media reported on Sunday.

"The voice and data recorders are at a special laboratory where, in the presence of Polish officials, including representatives of the Polish state prosecutor, work has begun on analyzing them," the Interfax news agency said.

Fragments of the fuselage, air traffic control recordings and the plane's "black boxes" are being studied, Russia's investigative committee said in a statement.

The bodies of Polish president Lech Kaczynski and his wife Maria will arrive in Poland at 1200 GMT Sunday from Russia, Polish radio reported, saying that the bodies would be carried by a military aircraft.

The chartered plane flying from Warsaw to the Russian city of Smolensk crashed in thick fog near the Smolensk airport on Saturday, killing all the people on board, including President Kaczynski and his wife, army chief of staff, deputy foreign minister and the central bank governor.