Aviation investigators have said Polish officials in the cockpit of the plane of president Lech Kaczynski that crashed in Russia put pressure on the crew to land in dangerous weather conditions.
Mr Kaczynski died with 95 others when his presidential jet crashed on 10 April last year.
It was attempting to land in fog near the city of Smolensk in northwestern Russia.
The damning report lists Polish shortcomings leading to the crash and risks increasing tension between the two countries.
The Russian inquiry suggests that the plane was ordered to land as Mr Kaczynski would have been unhappy if it was diverted.
Tatyana Anodina, head of the Moscow-based aviation commission investigating the tragedy, confirmed that top Polish officials had been in the cockpit of the Tu-154 plane but also revealed they had pressured the crew.
'The presence in the cockpit of high-ranking officials - Poland's air force chief and head of protocol - and the expected negative reaction from the main passenger put psychological pressure on crew members and affected decision making regarding the continuation of landing under any conditions,' she said.
She did not identify the 'main passenger' but it appears she was referring to Mr Kaczynski.
'Psycho-emotional tension' and a 'conflict of motives' were among key factors contributing to the crash, said Mr Anodina.
'There was a strong motivation to perform the landing precisely at the airport of destination,' she added.
In course of the flight, the crew 'repeatedly received information about the absence of adequate weather conditions' from the Severny airport in Smolensk, she said.
'Despite this, the Tu-154 crew did not make a decision to land at a substitute airport. This fact can be considered the start of a critical situation during the flight,' she said.
Ms Anodina said experts also found alcohol in the blood of the Polish air force chief Andrzej Blasik, who was present in the cockpit of the plane.
Mr Kaczynski's twin brother and opposition party leader Jaroslaw Kaczynski has said the report lacks evidence, is one-sided and insults Poland.
Mr Kaczynski said: 'The report puts the entire blame on Polish pilots and Poland without any proof ... The report is a joke against Poland.'
The Russian-made Tupolev-154 was carrying Lech Kaczynski as he prepared to attend a ceremony at Katyn forest commemorating the 70th anniversary of a World War II massacre of around 22,000 captured Polish officers by the Soviet secret police.
