|Disagreement over the commemoration plaque has prompted anti-Russian demonstrations in Poland [Reuters]
Poland has marked the anniversary of an aeroplane crash that killed its then president and many civil and military leaders, amid a diplomatic row over a plaque commemorating the event.
Ceremonies on Sunday honoured Lech Kaczynski, his wife Maria, and 94 others killed on April 10, 2010, when their aircraft crashed in thick fog while trying to land at Smolensk in western Russia.
Church bells rang out across Poland to mark the exact time a year ago that the crash occurred.
People filled churches and cemeteries, and a large crowd waving Polish flags gathered in front of the presidential palace, where Kaczynski and his wife Maria lived.
Earlier, the loved ones of many victims gathered for a private mass at Warsaw's airport, where last year 96 flag-draped coffins returned over several days to funeral marches.
But the commemorations have been overshadowed by the spat over the plaque at Smolensk.
Erected by the families of the crash victims the plaque described in Polish how Kaczynski's party died on their way to mark the 70th anniversary of "the Soviet crime of genocide against prisoners of war, Polish army officers".
Kaczynski and his team had been heading to Katyn forest near Smolensk to honour 22,000 Polish officers and intellectuals murdered by the Russian secret police in 1940, the event to which the plaque referred.
Russian authorities replaced the plaque on Saturday with a much shorter text, in both Russian and Polish, that omits all mention of the Katyn massacre and refers only to the air crash.
"This was a bad decision by the Russians," Marcin Bosacki, a Polish foreign ministry spokesman, said on TVP Info television.
"We would expect more sensitivity from them. We believe this will damage the spirit of this weekend's commemorations."
Andrei Yevseyenko, a spokesman for Smolensk's governor, said Poland had previously agreed to the removal of the original sign and its replacement with a bilingual plaque.
He said it was not necessary to mention Katyn on a plaque at the site of the crash.
The original Polish plaque will be transferred to a museum at Katyn dedicated specifically to the 1940 massacre, he said.
But the decision has incensed the families of the crash victims and prompted a protest, attended by up to 1,000 Poles, outside the Russian embassy on Saturday evening.
Bronislaw Komorowski, the Polish president, is expected to raise the issue with Dmitry Medvedev, the Russian president, when the two men visit Smolensk and Katyn on Monday.