WARSAW, Poland -- Russian investigators said there were no technical problems with the Soviet-made plane that crashed and killed the Polish president and 95 others over the weekend, suggesting pilot error may have been to blame.
The Tu-154 went down while trying to land Saturday in dense fog near Smolensk airport in western Russia. All 96 passengers and crew aboard were killed, including Poland's President Lech Kaczynski and dozens of political, military and religious leaders.
They had been traveling in the government-owned plane to attend a memorial at nearby Katyn forest honoring thousands of Polish military officers who were executed 70 years ago by Josef Stalin's secret police.
The pilot had been warned of bad weather in Smolensk, and was advised by traffic controllers to land elsewhere -- which would have delayed the Katyn observances.
Russian investigators have almost finished reading the flight recorders, Deputy Prosecutor General Alexander Bastrykin said.
"The readings confirm that there were no problems with the plane, and that the pilot was informed about the difficult weather conditions, but nevertheless decided to land," Bastrykin said during a briefing with Russian Prime Minister Vladimir Putin in Smolensk.
Bastrykin said the readings would be double checked, according to footage of the meeting broadcast Monday on Poland's TVN24.
The wreckage, meanwhile, will remain on site through midweek to help speed the investigation, Russian Deputy Transport Minister Igor Levitin said.
Both Russia and Ukraine declared a day of mourning Monday, as Poles struggled to come to terms with the national tragedy that eliminated so many of their government and military leaders.
Tens of thousands watched as Kaczynski's body, returned Sunday to Warsaw, was carried in a coffin by a hearse to the presidential palace.
An annual Holocaust memorial event at Auschwitz-Birkenau on Monday was honoring Kaczynski and the other victims. Organizers of the March of the Living -- with some 10,000 Jewish youth marching over a mile (1.6 kilometers) between the two parts of the former Nazi death camp -- said those marching would also remember Poland's elite killed in Saturday's crash.
Forensics experts from Poland and Russia were working to ID other bodies, including first lady Maria Kaczynski, using DNA testing in many cases. So far some 24 bodies have been identified, including Poland's civil rights commissioner, Janusz Kochanowski.
Also aboard the Tupelov were the national bank president, the deputy foreign minister, the army chaplain, the head of the National Security Office, the deputy parliament speaker, the Olympic Committee head and at least two presidential aides and three lawmakers.
The pilot was identified as Capt. Arkadiusz Protasiuk, 36, and the co-pilot as Maj. Robert Grzywna, 36. Also on the cockpit crew were Ensign Andrzej Michalak, 36, and Lt. Artur Zietek, 31.
Kaczynski's family, including his twin Jaroslaw Kaczynski, the former prime minister, has not yet decided on a date for a funeral or burial.
Russian President Dmitry Medvedev has said he wants to attend, according to Polish Foreign Minister Radek Sikorski.
The Polish president is survived by his mother, Jadwiga; twin brother, Jaroslaw; daughter, Marta, and two granddaughters.
Investigator walk at the site of the Polish presidential plane crash in Smolensk, western Russia, Monday, April 12, 2010. Polish President Lech Kaczynski, his wife and some of the country's most prominent military and civilian leaders died Saturday along with dozens of others when the presidential plane crashed as it came in for a landing in thick fog near Smolensk in western Russia. (AP Photo/Sergey Ponomarev)