The State Duma on Friday directly blamed Josef Stalin for the 1940 massacre of thousands of Polish officers at Katyn in a rare condemnation of the dictator, in a vote widely seen as an attempt by Moscow to improve ties with Poland.
The Duma voted in favor of a resolution saying documents in secret archives showed Stalin directly ordered the massacre, the body said on its web site. The resolution was backed by 342 of 450 members.
"Material, kept for many years in secret archives...bears witness to the fact that the Katyn crime was carried out under Stalin's direct orders," the resolution said.
"The State Duma deputies extend a hand of friendship to the Polish people and hope this will mark a new era of relations between our countries," it added.
Human rights campaigners have been alarmed by what they see as an attempt by some officials — especially during Prime Minister Vladimir Putin's years as president during 2000-2008 — to play down Stalin's atrocities by focusing on his achievements.
Katyn, a village near Smolensk, is one of a handful of sites across Russia where NKVD officers executed Polish prisoners of war. The Katyn graves, discovered by Nazi invaders in 1943, hold 4,000 bodies out of what Poland says is a total of nearly 22,000 victims.
While the original 1940 execution order signed by Stalin was declassified by then-President Boris Yeltsin, Friday's resolution is one of the strongest official censures of the wartime leader since the Soviet Union's collapse in 1991.
"This is really a question of conscience, after so many years of negation and silence, to make a declaration that would close this chapter of our history," said Konstatin Kosachyov, head of the Duma committee on foreign affairs.
Poland welcomed the decision, which comes after Putin paid his respects at Katyn on April 7 and after a plane crash on April 10 that took the life of Polish President Lech Kaczynski on his way to a separate Katyn service.
Kaczynski, his wife and 94 officials were all killed en route to a ceremony commemorating the massacre when their plane crashed and broke apart on treetops near Smolensk.
Analysts viewed Friday's resolution as a bid to boost ties with Poland. The Kremlin is making a rapprochement after decades of tension.
"If 10 years ago there were a lot of survivors — I mean from the side of those who participated in the repressions — now it's more like distant history," said Nikolai Petrov, an analyst with the Moscow Carnegie Center.
"So to come forward with this now means to improve the image of the country at a very low political cost," Petrov added.
Poland's foreign ministry said it was an important step towards full reconciliation between Poland and Russia.
"This gesture confirms that there is no way back from the road of a truth-based Polish-Russian dialogue," the ministry said in a statement, adding that it hoped the decision would be followed by a rehabilitation of the Polish victims.
Poland's center-right government also expects President Dmitry Medvedev to hand over more declassified files of the Katyn massacre to Warsaw during his visit slated for Dec. 6. Medvedev gave Poland some of the original files in April.
For nearly half a century, Moscow blamed Nazi Germany for killing the Polish officers.
It was not until 1990 that General Secretary Mikhail Gorbachev admitted that Stalin's NKVD, the precursor to the KGB, was responsible. But Gorbachev stopped short of directly accusing the dictator.
Virulent opposition to the resolution was voiced by the Communist Party, many of whose leaders still deny the NKVD's involvement in the massacre and admire Stalin for his role in leading Soviet troops to victory in World War II.
"How can we apologize for the Katyn tragedy when it wasn't our fault?" Communist Party member Viktor Ilyukhin said.
Rights group Memorial, which wages an often lonely battle to document Soviet-era repressions, hailed the move as a "serious step forward" but called for it to be followed by action.