Poland paid an emotional tribute to President Lech Kaczynski, his wife Maria and 94 others killed in a plane crash a week ago in Russia.

Up to 100,000 mourners, many clutching red-and-white national flags threaded with black ribbons, packed into the vast Pilsudski Square in central Warsaw to commemorate the victims of the country's most devastating accident since World War Two.

"They all had their dreams and hopes for the future of their homeland. This is a serious test for us to understand those hopes well and take them into the future," Prime Minister Donald Tusk, who had been a political rival of Kaczynski's, told the crowd.

"This is the most we can do for them. We are here to remember them. Poland is here to remember them. We will not forget," Tusk said.

Behind him on the podium a tall, white cross rose up between two large black panels bearing the portraits of all the dead, whose names an actor read out one by one.

Saturday's commemoration, which included a three-gun salute and a Roman Catholic requiem mass, came a day before the planned burial of Kaczynski and his wife in the crypt of Wawel cathedral in the ancient capital of Krakow in southern Poland.

World leaders including U.S. President Barack Obama were scheduled to attend the Wawel funeral. But a huge volcanic ash cloud drifting across Europe from Iceland has closed Polish airports and it was unclear how many would manage to come.