By Gareth Jones and Patryk Wasilewski
WARSAW (Reuters) - A diplomatic row has erupted over a plaque marking last year's plane crash in Russia that killed Poland's president and 95 others, casting a shadow over Sunday's commemoration of disaster's first anniversary.
The spat has laid bare the raw emotions still swirling among Poles one year on from the crash, which stunned their nation, exacerbated its political divisions and revived historic suspicions about Russia, their former Cold War master.
President Lech Kaczynski, his wife Maria, and a sizeable chunk of Poland's military and political elite died on April 10, 2010, when their plane crashed in thick fog while trying to land at Smolensk in western Russia.
They had been heading to Katyn forest near Smolensk to honor 22,000 Polish officers and intellectuals murdered by Soviet dictator Josef Stalin's NKVD secret police in 1940.
Families of the crash victims erected a plaque at Smolensk in the Polish language that described how Kaczynski's party died while trying to mark the 70th anniversary of "the Soviet crime of genocide against prisoners of war, Polish army officers."
But Russian authorities replaced it 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 plane crash.
"This was a bad decision by the Russians. We would expect more sensitivity from them. We believe this will damage the spirit of this weekend's commemorations," Polish Foreign Ministry spokesman Marcin Bosacki told TVP Info television.
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.
Families of the crash victims were incensed by the decision.
"I am shocked. This incident has undermined Russian credibility," said Malgorzata Szmajdzinska, widow of a leading Polish leftist politician who died in the crash.
"I think it was meant as a blow to the psyche of those who travel there and to our national psyche."
Polish President Bronislaw Komorowski is expected to raise the plaque issue with Russian President Dmitry Medvedev when the two men visit Smolensk and Katyn on Monday.
Up to 1,000 Poles protested outside the Russian embassy on Saturday evening, waving white and red national flags and banners branding Russian Prime Minister Vladimir Putin a "murderer" and Poland's Prime Minister Donald Tusk a "traitor."
The protesters, many of them supporters of the late president's twin brother Jaroslaw Kaczynski, leader of the main opposition party, believe Russia may have helped to engineer the crash and accuse the Tusk government of colluding with it.
They resent Tusk's efforts to build closer trade and energy ties with Moscow as part of a wider diplomatic rapprochement.
Many Poles have also been angered by an official Russian report into the crash, which concluded that sole responsibility lay with the Polish pilots. Polish officials say Russian ground control also bears some responsibility for the disaster.
The crash report has not only strained ties between Moscow and Warsaw but also deepened the rift between Tusk's government and Kaczynski's right-wing Law and Justice party (PiS).
Tellingly, Tusk and Kaczynski will attend separate church services, wreath-laying ceremonies and concerts during Sunday's day-long commemorations of the anniversary.
Even as the politicians bicker -- an election is due later this year -- an opinion poll last week indicated that a majority of Poles did not plan to mark Sunday's anniversary in any way and wanted the country to move on.
(Additional reporting by Lidia Kelly in Smolensk; writing by Gareth Jones; Editing by Kevin Liffey)