"Traces of explosives were detected on many pieces of the Tu-154M plane as well as on the body of at least one of the victims," the commission said as quoted by the Polish Press Agency (PAP).
Meanwhile, the commission stated that the samples of soil collected at the site of the aircraft crush did not contain traces of any explosive substances.
Commenting on claims that Russia might bear responsibility for the accident, Russian President Vladimir Putin has argued that the explosives might have been taken aboard in Poland and recalled that findings of the first Polish commission into the plane crash said that the pilots' erroneous actions could have been the cause for the tragedy.
On April 10, 2010, a Russia-made Tu-154M passenger plane carrying Kaczynski, his wife, and a number of high-ranking Polish officials crashed as it attempted to land at an airfield covered in heavy fog near Smolensk. None of the 96 passengers aboard the plane survived.