The upcoming visit by Russian Prime Minister Vladimir Putin to Katyn, where thousands of Polish POWs were massacred by Soviet forces in WWII, demonstrates a "new trend in Russia's approach to history," a Polish politician said on Monday.

Putin will visit the western Russian location on April 7 to take part in a memorial service marking the Katyn massacre. Polish Prime Minister Donald Tusk is also expected to attend the ceremony, while Polish President Lech Kaczynski is to travel to Katyn on April 10.

"The very fact that Russian Prime Minister Vladimir Putin will visit Katyn and honor the memory of the victims of the Katyn tragedy is an event of huge importance," Andrzej Przewoznik, who heads Poland's council for the protection of the memory of World War Two victims and veterans, said.

Over 20,000 Polish officers, police and civilians taken prisoner during the 1939 partitioning of Poland by the Soviet Union and Nazi Germany were killed in the Katyn forest in 1940, as well as in prisons and other locations, by the NKVD, the forerunner of the KGB.

Przewoznik expressed hope on Monday that Russia would unveil its archives related to the Katyn massacre, which still remain closed. He said the documents were "important" as they would help learn about "destinies of people, who fell victims to the communist system", including those of victims of the Katyn massacre.

The Soviet Union acknowledged the massacre in 1990. Modern Russia also recognized Soviet responsibility for the mass shooting, but has not classified it as a war crime, something Warsaw has demanded.

The two Slavic nations have recently been at odds over Soviet leader Joseph Stalin's 1939 deal with Nazi Germany, which Warsaw says triggered the invasion of Poland and the start of WWII.

Putin moved to heal the rift over the massacre and the 1939 deal when he visited Poland in September to mark the 70th anniversary of its invasion. He called the killings "a crime" but urged "forgiveness." He said all European countries bear their share of responsibility for the outbreak of the war.

WARSAW, April 5 (RIA Novosti)