The ageing Tupolev Tu-154, which crashed Saturday morning in western Russia killing President Lech Kaczynski and many others had recently undergone thorough mechanical overhaul, reports Polish Radio.

Foreign Ministry spokesman Piotr Paszkowski says that the cause of the accident is not yet clear.

Eye witnesses say that heavy fog surrounded the airport near Smolensk and the plain attempted to land four times before clipping to the tops of trees and immediately falling to the ground, where it burst into flames.

The airport was closed at the time of the attempted landing with visibility down to less than 500 meters, according to Russian TV reports. The pilot was offered alternative landings at either Moscow or Minsk airports but decided to try and land at Smolensk.

The aircraft was just one kilometre short of the runway when it crashed. (pg)