Russia has handed over more documents on the World War II Katyn massacres to Poland, ahead of an upcoming visit by President Dmitry Medvedev to Warsaw.
The 1940 massacre of some 20,000 Polish officers and other prominent citizens in western Russia by Soviet secret police has long soured relations between the two countries.
Polish Prime Minister Donald Tusk welcomed the move as "an important step," and said Warsaw wanted to receive all the files on the killings in order to bring the issue to a "dignified conclusion."
Moscow also handed over a batch of documents on the Katyn massacre in May 2010.
compiled from agency reports