10 April 2012 Last updated at 10:15 ET

Poland commemorates Smolensk plane crash victims

Wreaths and candles were placed outside the presidential palace to commemorate the dead

Poland is marking the anniversary of the 2010 plane crash that killed its president Lech Kaczynski and 95 others.

Ceremonies took place at Powazki military cemetery in Warsaw, and at the crash site near a military airfield in Smolensk, western Russia.

However the late president's twin, Jaroslaw Kaczynski, boycotted the state ceremonies for the second year running and attended separate events.

He claims that the crash was an assassination.

All 96 passengers and crew were killed in the crash in 2010, when the plane attempted to land in foggy weather.

Several Polish politicians and officials, including the first lady, Maria, had been on board. They had been travelling to Russia to mark the 70th anniversary of the Katyn massacre of more than 20,000 Polish officers on Stalin's orders by Soviet secret police during World War II.

Prime Minister Donald Tusk took part in Tuesday's ceremony with some of the victims' relatives in Powazki military cemetery, where many of the crash victims are buried.

President Bronislaw Komorowski attended a Mass in Warsaw, and laid flowers at a plaque commemorating the dead.

Polish Culture Minister Bogdan Zdrojewski and Russia's Parliament Speaker Sergei Naryshkin also laid wreaths in a ceremony at the crash site in Smolensk.

Boycott

Jaroslaw Kaczynski, who leads Poland's opposition Law and Justice party, attended an alternative ceremony outside the presidential palace.

He said recently that he believed his brother was assassinated, and an unofficial investigation by his party concluded that there were two explosions before the plane crashed in heavy fog near the runway.

While many in Poland find the assertions ridiculous, there is widespread disapproval of the Russians absolving themselves of any blame for the crash, the BBC's Warsaw correspondent Adam Easton says.

Both the official Russian and Polish investigations have said that pilot error was the main cause of the crash.

However, the Polish investigation also said that the actions of the Russian air traffic controllers contributed to the disaster.

Lech Kaczynski's daughter, Marta Kaczynska, told Polish media that the sadness she felt when she first learned of her parents' death returned to her every day.

"I would like to express my gratitude to all those who remember my parents and have the courage to show it," she said.