Lech Kaczynski, the Polish president at the time of the crash, and other Polish government officials died April 10, 2010, when their Tu154 plane crashed during landing near the Russian city of Smolensk.
On Jan. 12 the Russian CIS International Aviation Committee released a report pointing to pilot error as the primary cause of the crash, which occurred when the plane hit trees during a landing attempt in thick fog, Russia's RIA Novosti reported Wednesday.
The late president's brother, Jaroslaw Kaczynski, the Polish opposition leader, said in Warsaw Russia's report on the crash's causes should be rejected.
Kaczynski criticized the committee's report for its "full and one-sided blame" of the Polish pilots.
"We put forward a resolution which rejects the (Russian) report. The Russian side is to blame for direct causes of the tragedy. We want to know the truth. Russia will have to take the international opinion into account," Kaczynski said.
Polish officials and experts also have found fault with the report, saying it doesn't have sufficient evidence for its conclusions.