Akhir 27, 1432 H/April 1, 2011, SPA -- The April 2010 plane crash that killed Polish president Lech Kaczynski and 95 others was not caused by any kind of terrorist attack, dpa quoted Polish military prosecutors as saying Friday. There are no reasons to suspect a terrorist attack, said Colonel Ireneusz Szelag, head of the district prosecutor's office Friday, citing multiple studies commissioned by authorities. Those studies found no signs of explosives or radioactive substances, said Szelag. Fuel levels were also correct, he said. The April 10, 2010 plane crash in Smolensk claimed dozens of prominent Poles on their way to Smolensk, Russia, for a commemoration of a 1940 massacre of Polish military officers and other citizens by the Soviet military. A Russian commission in January blamed the crash on the plane's Polish pilots. But Kaczynski's twin brother, Jaroslav, and other members of his Law and Justice party have stoked speculation about an explosion or artificially created fog at the crash site as a possible cause for the accident. There has been speculation in Poland that Russian air controllers bear some of the blame for the crash. A Polish study on the question is due later this year. A commemoration ceremony for the plane crash is scheduled for April 11. Russian President Dmitry Medvedev and Polish President Bronislaw Komorowski are both set to attend.