The plane carrying Mr Kaczynski’s body arrived from the airport in Smolensk, Russia, where he and 95 others had been heading on Saturday to honour 22,000 Polish officers slain by the Soviet secret police in 1940.
Kaczynski’s twin brother, Jaroslaw, knelt on the ground and pressed his head against the flag-draped coffin before rising and crossing himself.
The coffin was escorted by 10 soldiers from the back of the plane as sombre music played. Warsaw Archbishop Kazimierz Nycz was among seven priests and military chaplains who led prayers at the airport and sprinkled holy water on the coffin.
There was no sign of the twins’ ailing mother Jadwiga, who has been hospitalised. The president had cancelled several trips lately to be by her side.
Also on the tarmac were Polish Prime Minister Donald Tusk and Marta Kaczynska, the only child of the president and his wife, Maria, who also perished in the crash.
Thousands of people stood silent in the streets to mourn Kaczynski and the dozens of political, military and religious leaders killed in the crash that ravaged the top levels of Poland’s elite.
Church bells pealed at noon and emergency sirens shrieked for nearly a minute before fading into silence. Hundreds bowed their heads, eyes closed, in front of the presidential palace. Buses and trams halted in the streets. No date for a funeral has been set.
The death of the president and much of the state and defence establishment in Russia, en route to commemorating one of the saddest events in the neighbouring nations’ long, complicated history, was laden with tragic irony.
“He taught Poles how to respect our traditions, how to fight for our dignity, and he made he made his sacrifice there at that tragic place,” said mourner Boguslaw Staron, 70.
Among the dead were Poland’s army chief of staff, the navy chief commander, and heads of the air and land forces.
At the Field Cathedral of the Polish Army in Warsaw, hundreds gathered for a morning Mass and left flowers and condolences.
Government spokesman Pawel Gras said the country’s armed forces and state offices were operating normally despite the losses.
The acting president, Parliament Speaker Bronislaw Komorowski, said he would call for early elections within 14 days, in line with the constitution. The vote must be held within another 60 days.
Kaczynski had indicated he would seek a second term in presidential elections this autumn but was expected to face an uphill struggle against Komorowski and his governing party, the moderate, pro-business Civic Platform.
Kaczynski’s nationalist conservative Law and Justice Party could benefit, however, from the support of a country mourning the loss of their president, particularly with elections now set to take place by late June.
In Moscow, Russia’s transport ministry said Russian and Polish investigators had begun to decipher flight data recorders of the aging Soviet-built Tu-154 airliner that crashed while trying to land in deep fog.
Russian officials had said 97 people were killed but revised the figure to 96.
The Smolensk regional government said Russian dispatchers had asked the Polish crew to divert from the military airport because of the fog and land instead in Moscow or Minsk.
Former president, Solidarity founder and Nobel Peace Prize laureate Lech Walesa, said it was too soon to cast blame.
“Someone must have been taking decisions on that plane. I don’t believe that the pilot took decisions single-handedly,” he said. “I’ve flown a lot and whenever there were doubts, they always came to the leaders and asked for a decision.”
Polish-Russian relations had been improving recently after being poisoned for decades over the slaying of some 22,000 officers and others in Katyn forest and in other areas. About 4,000 Polish army officers were killed in the forest by Josef Stalin’s NKVD, the forerunner to the KGB, in 1940
Russia never has formally apologised for the murders but Russian Prime Minister Vladimir Putin’s decision to attend a memorial ceremony earlier this week was seen as a gesture of goodwill toward reconciliation.
Kaczynski wasn’t invited to that event because Putin, had invited his Polish counterpart, Donald Tusk.
Kaczynski’s twin brother flew to Smolensk on Saturday and identified the body of his brother and sister-in-law.
President Dmitry Medvedev declared today a day of mourning in Russia.