Gdansk, Poland - Russian Prime Minister Vladimir Putin and his Polish counterpart, Donald Tusk, said Tuesday that an examination of the tragic events in their countries' past could help build trust amid recent strains in relations between Warsaw and the Kremlin.

"Only in searching for the truth about the sources of dramatic events ... we will be able to build understanding and greater trust between our politicians, but most of all between our nations," Tusk said after meeting Putin in the resort city of Sopot for ceremonies marking the 70th anniversary of the outbreak of World War II.

Tusk called Putin's visit an "important gesture" in what was the Russian leader's first visit to Poland since 2005.

The two prime ministers met face-to-face for a half-hour session, discussing economic issues and the controversial issue of the 1940 Katyn Forest massacre, in which Soviet security police killed some 4,000 Polish officers.

"We have problems in history that we must carefully analyze and everything that led to the tragedy of 1939 (must also be analyzed). And that's why we want that tragedy never to be repeated," Putin said, calling for both sides to come together and study history without mutual accusations.

Poland has sought Russia's release of the documents it holds on the Katyn massacre, which Poland says it needs as proof to bring the perpetrators of the killings to justice.

Putin said that Russia will "open its archives if Poland opens its archives."

But Poland's archives were already open to international scholars, an official from the Institute of National Remembrance - which investigates Soviet and Nazi crimes - told broadcaster TVN24 shortly after Putin's comment.

Later Tuesday, Putin was to be joined at the Westerplatte peninsula on the Baltic coast by German Chancellor Angela Merkel and delegations from 31 countries for ceremonies marking the start of history's bloodiest conflict.

At sunrise Tuesday, Tusk and Polish President Lech Kaczynski Polish leaders gathered with veterans and Gdansk's archbishop to mark the moment a Nazi battleship fired its first shots at the military garrison to spark World War II.

Tensions were heightened before Putin's visit when Russian state television station Vesti showed a documentary that said a 1934 Polish-German treaty laid out plans to invade the Soviet Union.

Putin struck a conciliatory note Monday when he condemned the Molotov-Ribbentrop Pact that divided Poland between Berlin and Moscow and said Russians "understand well" Pole's feelings over Katyn. (dpa)