The crash traumatised Poland Russia has blamed the Smolensk air crash which killed the Polish president and nearly 100 other people in April on Polish pilot error.
Air crash investigators revealed their findings in Moscow after handing their final report into the disaster to their Polish colleagues.
Polish officials criticised a draft version last month, describing it as negligent and riddled with errors.
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 came down in heavy fog near the western Russian city of Smolensk.
They had been on their way to a memorial ceremony for Poles massacred by Stalin’s secret police at Katyn during World War II.
Last month, Polish Prime Minister Donald Tusk described a draft of the Russian report as “unacceptable”, saying some of its conclusions were unfounded.
Without revealing details, he said it did not comply fully with the Chicago Convention which regulates international air travel.
“This negligence and mistakes, or lack of positive reaction to what Poland has been asking for, all these things allow us to say that some of the report’s conclusions are without foundation,” he added.
In another development, Lech Kaczynski’s twin brother, former Prime Minister Jaroslaw Kaczynski, has said he doubts that the body entombed in a Polish cathedral last year is that of his brother.
“When I saw the body that was brought back in a coffin to Poland, that person did not look like my brother,” he told reporters last month.
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