WARSAW, Poland (AP) — A Polish court on Thursday found the chief of staff for former Polish Prime Minister Donald Tusk guilty of negligence in a 2010 presidential flight to Russia which ended in a devastating crash that killed President Lech Kaczynski and 95 others.

The provincial court in Warsaw ruled that Tomasz Arabski had exposed the president to danger by allowing a hazardous flight to travel to a rudimentary airport in Smolensk, Russia. Arabski was given a 10-month suspended prison sentence that is subject to appeal.

Prosecutors argued that Smolensk airport should not have been considered as a destination for the presidential flight and that many other mistakes were made during preparations for the presidential trip. They blamed Arabski and demanded a 1.5-year suspended prison term.

Arabski says he is innocent of the charges.

Polish investigators have blamed the crash on human error in bad weather and poor guidance by Russian traffic controllers.

But Kaczynski's twin brother, Jaroslaw Kaczynski, the current leader of Poland's nationalist ruling Law and Justice party, has blamed the crash on negligence by Tusk's government, which was critical of his brother, the president. He especially blames Tusk, his long-time political rival, who is now the head of the European Council.

President Kaczynski, first lady Maria Kaczynska and scores of high Polish government and military officials died in the April 10, 2010, crash as they were arriving in Russia for ceremonies honoring Polish officers killed by the Soviet secret security in 1940 during World War II.

For many years, Jaroslaw Kaczynski led monthly observances in Warsaw in their honor.

Russia is refusing to return the plane's wreckage, arguing that it is needed for a continuing investigation.