The aircraft carrying President Kaczynski, his wife and dozens of senior government officials and commanders of the Polish armed forces crashed as it came in to land at a military airfield near Somlensk, in western Russia, at 8:41 a.m., on April 10, 2010.
The delegation was on its way to nearby Katyn to attend events marking the 70th anniversary of the 1940 Katyn Massacre, in which close to 22,000 Polish POWs, mainly army officers, policemen and administrative staff, were murdered at the hands of the Soviets.
To mark the anniversary, sirens wailed at 8:41 a.m. in many Polish towns on Sunday to honour the victims of the tragedy.
The decision to use the sirens was sharply criticised by the opposition and some local governments, which said it could have caused anxiety among war refugees from Ukraine and trigger war-related stress.
The Interior Ministry had stated earlier that a text message alert had been sent to Ukrainians, who possessed SIM cards which were logged into Polish mobile networks, to inform them that sirens would be turned on.
Wreaths were laid and candles were lit at monuments commemorating Lech Kaczynski and the other victims in Pilsudski Square in central Warsaw, and across Poland.
Flowers were also laid by Polish diplomats at the site of the air crash.
Leaving Wawel Castle in Krakow, where the presidential couple is buried, President Andrzej Duda said that this year's observances of the Smolensk air disaster had a special poignancy owing to the war in Ukraine.
"Today, we can see photos of a destroyed Ukraine, we can see the bodies of the murdered people. Just like then, when we saw a destroyed airplane, and the bodies of the people killed in the air disaster," Duda said
Jaroslaw Kaczynski, the twin brother of the late president and leader of Law and Justice, Poland’s governing party, has long maintained his brother was assassinated. (PAP)
at/md/jch