Russian investigators say they are unable to reach a final conclusion about what caused the 2010 plane crash that killed Polish President Lech Kaczynski and 95 others because Poland has not responded to requests for certain information.
In a statement issued a day before the fifth anniversary of the crash, the investigators said most of their work was done, but the lack of requested information from Poland was one of the things preventing them from closing the case. They did not specify what Poland had been asked to supply.
Polish investigators have blamed the crash on the crew's decision to go ahead with the landing despite dense fog. They also have named two Russian flight controllers as suspects.
The Russian investigators on Thursday denied the flight controllers were to blame.