Pilot error was suspected of causing the crash, a spokesman for the Smolensk government said.

Andrei Yevseyenkov, the local government's spokesman, said "the pilot was advised to land in Minsk, but decided to land in Smolensk."

A source with the investigation committee told the Interfax news agency that bad weather, human error and mechanical fault were considered the possible reasons behind the tragedy.

A security source told the RIA Novosti news agency that human error was most likely to blame for the crash.

"A mistake by the crew during landing maneuvers has supposedly caused the crash," the unnamed source said.

A chartered plane carrying Polish President Lech Kaczynski crashed near the Smolensk airport in western Russia Saturday, killing all 96 people on board, said Russian officials.

Earlier reports put the number of people on board the plane at 132, but Russia's Emergency Ministry later corrected it as 96. Among them, 88 belong to the Polish delegation.