WARSAW, April 11 (Xinhua) -- A special commission under former Polish Defence Minister Antoni Macierewicz has refuted the 2011 findings of a government commission investigating the 2010 Smolensk air crash that stated pilot error as the cause, Polish Press Agency reported Wednesday.

According to the Macierewicz commission's technical report on the incident published Wednesday, the air crash's main cause was a series of mid-air explosions inside the machine.

Presenting the report, Macierewicz said that it was not the final and only addressed the technicalities of the crash, therefore it threw no light on claims that the disaster may have been masterminded. He added that his commission's full report could be expected in about a year.

Commenting on the 2011 report, Macierewicz said, "The commission decided that the (2011) report not only contained false claims, but was prepared under political pressure... and based on manipulated materials."

According to the Macierewicz commission, clear proof of explosions inside the Smolensk plane was provided by one of the wing fragments, which carried disfigurations caused only by explosions.

On April 10, 2010, a Polish government Tupolev with then Polish President Lech Kaczynski, his wife and a large official delegation crashed during an attempted landing through heavy fog on a military airfield in Smolensk. The delegation were travelling to the Russian locality Katyn for anniversary ceremonies of the 1940 Katyn Forest mass executions of 22,000 Polish prisoners of war (POWs) by the Soviet security units.