Poland mourns President Lech Kaczynski after jet crash
Crowds sang the Poland's national anthem at the presidential palace
Church services are being held across Poland to start a week of mourning for President Lech Kaczynski and 95 others, killed in a jet crash in Russia.
Floral tributes and written condolences have been laid at churches in Warsaw, and a two-minute silence is planned.
The president, military chiefs, MPs and cultural figures were due to attend a memorial for a World War II massacre when their plane crashed near Smolensk.
Russian officials say pilots ignored warnings that they were flying too low.
Polish officials said Mr Kaczynski's body would arrive back in the country in the afternoon.
Russia has declared Monday a day of mourning and Russian Prime Minister Vladimir Putin, who visited the crash site with Polish counterpart Donald Tusk, said he would oversee the investigation into the crash.
"Everything must be done to establish the reasons for this tragedy in the shortest possible time," he said.
Earlier in the week, Mr Putin and Mr Tusk had attended a memorial for the victims of the 1940 Katyn massacre.
Mr Putin has played a leading role in admitting Soviet culpability in the massacre, when thousands of Poles were killed by Soviet secret police, and this year was the first time that Russia had held memorials.
Mr Tusk, who returned to Russia on Saturday along with the late president's twin brother Jaroslaw, described the crash as the most tragic event of the country's post-World War II history.
Witnesses said the plane approached Smolensk air base with its left wing pointing to the ground. It clipped trees as it came down and crashed, scattering debris across a forested area.
The deputy head of Russia's air force said the pilots had ignored repeated requests from air traffic controllers to divert the flight to another airport to avoid the heavy fog around Smolensk.
About 1.5km (0.9 miles) from the air base, air-traffic controllers noticed the jet was below the scheduled gliding path, said Lt Gen Alexander Alyoshin.
Ground control "ordered the crew to return to horizontal flight, and when the crew did not fulfil the instruction, ordered them several times to land at another airport," he said.
"Nonetheless the crew continued to descend. Unfortunately this ended tragically."
The Polish Foreign Ministry confirmed that 96 people were on board the flight, after Russian officials had earlier said 97 people had been killed.
Russia's Emergencies Minister Sergei Shoigu said both of the plane's flight information recorders had been found and were being examined.
Soviet secret police shoot dead more than 20,000 Polish prisoners-of-war, drawn mainly from the political, military and cultural elite
For 50 years, Soviet authorities blame Nazis for slaughter
In 1990, Soviet leader Mikhail Gorbachev admits Soviet responsibility
Vladimir Putin's invitation to memorial seen as attempt to resolve issue, which has continued to blight Polish-Russian relations
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