Russia has blamed the Smolensk air crash which killed the Polish president and nearly 100 other people in April on Polish pilot error.
The Polish crew failed to heed bad weather warnings because they were afraid of displeasing President Lech Kaczynski, Russian investigators said.
The pilots were driven to take "unjustified risk", they found.
Poland's interior minister accepted the findings but said Russian officials had also been at fault.
Polish Prime Minister Donald Tusk cut short a holiday in response to the report and was returning to Poland for talks with the minister, Jerzy Miller.
In other reaction, Lech Kaczynski's twin brother Jaroslaw condemned the Russian report as a "joke against Poland", saying the Russian investigators had failed to produce evidence.
Russia's handling of the disaster had previously been widely commended.
President Lech Kaczynski and 95 others, spanning the country's military and political elite, were killed when their airliner crashed while trying to land in heavy fog near the western Russian city of Smolensk. There were no survivors.
They had been on their way to a memorial ceremony for Poles massacred by Stalin's secret police at Katyn during World War II. BBC News
