Polish Prime Minister Donald Tusk described the crash as “the most tragic event of the country’s post-war history”.
Ashen-faced and wearing a black suit and tie, Mr Tusk told a news conference he would fly to the crash site.
Russian Prime Minister Vladimir Putin talked to Mr Tusk by telephone and has also gone to the scene of the crash, a spokesman said. The death of Kaczynski, who with his twin brother was a dominant force in Polish politics, brings political uncertainty. A presidential election had been due in October but now must be held within two months, according to the Constitution.
The President’s wife and several other high-ranking government officials also were aboard the aged Tupolev Tu-154, which plunged into a forest about two kilometres from the airport in the western Russian city of Smolensk.
Pilot error was a possible reason for the crash, said Andrei Yevseyenkov, spokesman for the Smolensk local government. Local officials said the plane had clipped treetops on its way down. Thousands of mourners gathered outside the presidential palace, laying flowers, lighting candles and saying prayers. Church services in the predominantly Catholic country were hastily arranged. Kaczynski, 60, was a one-time ally of Solidarity hero Lech Walesa and a co-founder of the rightist Law and Justice party with his brother.
He resigned from the party when he became President in 2005 but continued to support it.
A party official told Reuters the President’s twin, Jaroslaw Kaczynski, had left for Smolensk.
Kaczynski’s death, along with that of many senior members of law and justice who also were on board, at a stroke changes the Polish political scene by wiping out much of the Opposition.
“The political consequences will be long term and possibly will change the entire future landscape of Polish politics,” said Jacek Wasilewski, professor at the Higher School of Social Psychology in Warsaw.
While the President’s role is largely symbolic, the holder can veto government legislation. Lech Kaczynski infuriated Mr Tusk’s government several times by blocking legislation including health sector reform. The Speaker of the Lower House of Parliament, Bronislaw Komorowski, has been named acting President, as the Constitution stipulates. Komorowski is also Mr Tusk’s presidential candidate in the centrist Civic Platform party.
Russian television showed the smouldering fuselage and fragments of the plane scattered in a forest. A Reuters reporter saw a broken wing some distance from the rest of the aircraft.
The plane was one of two Tu-154s in the government fleet, both about 20 years old. Government officials had complained about the age of Poland’s official fleet.
Russia’s emergencies ministry said 97 people were aboard, including 88 members of a Polish delegation en route to commemorate Poles killed in mass murders in the town of Katyn under orders from Soviet leader Josef Stalin in 1940.
Smolensk regional governor Sergei Antufyev said there were no survivors of the crash. The emergencies ministry said the bodies of the victims would be transported to Moscow for investigation.
A Russian mission control official who was present during conversations with the pilot said the pilot had ignored advice.
“The pilot was advised to fly to Moscow or Minsk because of heavy fog, but he still decided to land. No one should have been landing in that fog,” he said, on condition his name was not published.
A Russian military official was quoted by Interfax news agency as saying air traffic control instructed the pilot several times to divert to another airport.
Polish justice minister Krzysztof Kwiatkowski planned an inquiry into the crash. Russian President Dmitry Medvedev said Russian investigators would cooperate with the Polish side.
Among the other casualties of the crash were Kaczynski’s wife Maria, along with Slawomir Skrzypek, 47, who had been central bank governor since 2007, the chief of Poland’s military Franciszek Gagor and deputy foreign minister Andrzej Kremer.
Analysts said Polish markets would not be severely jolted. “Although tragic, we do not believe that this event threatens political and financial stability in Poland in any fundamental way,” Goldman Sachs said in a research note.
Some relatives of victims of the Katyn massacres also were on board, said a Polish government official in Smolensk. Thousands of Polish prisoners of war and intellectuals were murdered at Katyn by Soviet forces in spring 1940 in an enduring symbol for Poles of their suffering under Soviet rule. The government declared a week of national mourning. “I’m all broken up ... it cannot be expressed in words,” said Ewa Robaczewska from outside the palace.
Lidia Kelly