Poland is marking the fifth anniversary of the plane crash that killed President Lech Kaczynski and 95 members of his presidential entourage on a visit to Russia, the worst catastrophe to strike the Polish state since World War II and an event that deepened historical strains between the two Slavic neighbors.

The president's daughter, Marta Kaczynska, who also lost her mother in the disaster, placed flowers early Friday at their grave at Wawel Cathedral in Krakow.

In Warsaw, Parliament Speaker Radek Sikorski and other parliamentary leaders placed wreaths in the building to remember the 18 lawmakers who were also killed near Smolensk, Russia.

Many other commemorations are scheduled throughout the day, including a ceremony at the military ceremony in Warsaw attended by the president, prime minister and other leaders.