Investigators say top Polish officials in the cockpit of the plane of President Lech Kaczynski, that crashed in Russia put pressure on the crew who ignored advice to land at a different airport.
President Kaczynski and 95 others died when the jet crashed on 10 April last year as it attempted to land in fog near the city of Smolensk in northwestern Russia. 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.
The head of the Aviation Commission investigating the tragedy, Tatyana Anodina, has confirmed that top Polish officials were in the cockpit of the Tu-154 plane and said they had pressured the crew.
The commission found that the presence of Poland's air force commander in the cockpit drove them to take "unjustified risk".
It also said the pilot and co-pilot had feared a "negative reaction" from President Kaczynski if they switched to the other airfield, according to the Russian investigator.
The flight recorder caught one of the crew saying "He'll get mad", in an apparent reference to the president's determination not to alter his schedule.
A foreign ministry official also entered the flight deck at one point.
Former Polish prime minister Jaroslaw Kaczynski said that the Russian report put "the entire blame on Polish pilots and Poland without any proof". He described the report as a "joke against Poland".
