Lech Kaczynski, the Polish president, will be buried alongside his wife on Saturday at the end of an official week of mourning.
Russian investigators have said there was nothing technically wrong with the plane that crashed killing the president and 95 others on its way to a memorial service in Smolensk.
Some have suggested that the pilots may have been pressured by people aboard the plane to land quickly so as not to miss the ceremony they were due to attend, which had previously been denied.
Al Jazeera's Jonah Hull reports from Warsaw.
