This article :
Lenta.ru: В мире: Экипаж самолета Качиньского игнорировал команды руководства аэродрома (in russian) says the following (translated by Google with my edits):
The crew of the Tu-154 of Polish President Lech Kaczynski repeatedly failed to comply with instructions of chief controller (title?) of airfield "Smolensk". This, according to ITAR-TASS, said Deputy Chief of Staff of the Russian Air Force Lt. Gen. Alexander Aleshin. According to him, a flight controllers at a distance of 1.5 kilometers discovered that the Tu-154 increased the vertical velocity and reduced the height of flight.
Chief controller gave the order to transition the aircraft to level flight, and when the crew failed to comply with instructions, several times he gave the command to use the alternate airfield. Nevertheless, the crew continued to descend" - added Aleshin.