Polish President Lech Kaczynski and some of Poland's key civilian and military leaders died Saturday when their chartered plane crashed, killing 97, as it came in for a landing in western Russia.

The 26-year-old Tupolev Tu-154 was enroute from Warsaw to Smolensk, Russia, when it went down in thick fog with the president, his wife, the army chief of staff, Deputy Foreign Minister Andrzej Kremer and the central bank governor aboard, said Polish Foreign Ministry spokesman Piotr Pszkowski.

Initial reports put the number of people on board the plane at 132, but Russia's Emergency Ministry later corrected the total to 96, then 97 in its latest announcement.

The victims included a delegation of 88 Poles headed to Russia to attend events marking the 70th anniversary of the massacre in Katyn forest of thousands of Polish officers by Soviet secret police.

The body of President Kaczynski may have been found in the wreckage of the plane, a highly-placed police source told RIA Novosti.

Speaking from the scene, the source said however that additional tests, including DNA, would be needed to identify many of the bodies.

The deaths were not expected to directly affect the functioning of Polish government: Poland's president is commander in chief of its armed forces but the position's domestic duties are chiefly symbolic. Most top government ministers were not aboard the plane.

Sergei Antufiev, governor of the Smolensk region,told Russia-24 television news network that the plane "clipped the tops of the trees, crashed down and broke into pieces."

Russian television showed the plane's wreckage scattered in a forest with parts still on fire. The plane's two black boxes have been found and are being analyzed by Russian investigators.

Andrei Yevseyenkov, a spokesman for the Smolensk government, said Russian dispatchers asked the crew to divert from Smolensk and land instead in Minsk, the capital of neighboring Belarus, or in Moscow because of the fog.

"The pilot was advised to land in Minsk, but decided to land in Smolensk," the spokesman said.

While traffic controllers generally have the final word in whether it is safe for a plane to land, they can and do leave it to the pilots' discretion.

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

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

The Interfax news agency cited the deputy head of Russian air force headquarters as saying air traffic controllers had advised the pilot not to land at the airport due to heavy fog, but the suggestion was ignored.