Lech Kaczynski

The president and 95 fellow passengers on the 20-year-old Tupolev-154 aircraft were on their way to Russia from Warsaw, Poland to attend the 70th anniversary service for the victims of the Katyn (Russia) massacre in 1940, when thousands of Polish prisoners of war, mainly military personnel, were murdered by the Soviet NKVD.

The aircraft crashed as it made one of several approaches to land at the airport in Western Russia in dense fog. Pilot error has been blamed for the tragedy after reports emerged that he ignored air-traffic controllers request to land at an alternative runway because of the fog. Witnesses said the pilot made three or four attempts to land before crashing into woodlands near the runway. There were also speculations that the pilot may have persisted in landing in adverse conditions, as he was pressured by officials on board to make the landing so that the contingency would be on time for the memorial function. There were no survivors of the crash.

Other officials killed included the Army chief of staff, National Bank President, Deputy Foreign Minister, former President Ryszard Kaczorowski - Poland's last president-in-exile, the head of the National Security Office, and Anna Walentynowicz, one of the original founders of Poland’s Solidarity Freedom Movement.

Thousands of Polish citizens bearing lit candles and flowers lined the streets of Warsaw to mourn the return of the casket of President Kaczynski on Sunday and the late first lady on Monday. The caskets were transported to the nation’s presidential palace where they were to lie in state, to be viewed by mourners during the week of mourning that ends on Saturday.

Reports are that Polish officials have long discussed replacing the planes that carry the country's leaders but said they lacked the funds. According to the Aviation Safety Network, there have been 66 crashes involving Tu-154s, including six in the past five years. The Russian carrier Aeroflot recently withdrew its Tu-154 fleet from service. Polish officials said that the plane that crashed was comprehensively overhauled last December.

Russian Prime Minister Vladimir Putin was awaiting the arrival of the Polish delegation at the memorial service at the Katyn monument when news of the crash arrived. According to the Kremlin, Putin has been put in charge of a commission investigating the crash.

Kaczynski assumed the presidency in December 2005. He was the twin brother of Poland’s opposition leader and former Prime Minister, Jaroslaw Kaczynski.

According to the Polish Constitution, the country’s Parliament speaker Bronislaw Komorowski has taken over duties as acting president.

Tributes on the Polish tragedy have been pouring in to Warsaw. These include tributes from President Barack Obama, Queen Elizabeth II of Britain, and the leaders of most European countries.