FRANKFURT, West Germany (AP) _ Europe today paid solemn tribute to the millions of victims of World War II, which started 50 years ago on Sept. 1 when a German warship opened fire on a tiny Polish garrison.

Adolf Hitler's troops quickly overran Poland, and the war spread around the globe. In the end, 50 million people had died.

By then the Nazis had shocked the world with the extermination of 6 million Jews, and the United States had forever changed warfare by dropping nuclear bombs on Hiroshima and Nagasaki in 1945.

Many of Belgium's 6 million Dutch speakers woke up to a broadcast of Hitler declaring war on Poland. BRT state radio opened its foreign news report with a tape of the original declaration and Germans cheering for their fuhrer.

In London, a reunion was planned of some of the people who were evacuated during Hitler's savage Blitzkrieg bombings of the city.

Italy's leading daily, the Milan-based Corriere della Sera, told its readers that ''Europe paid the price of its lacerations with the loss of its political supremacy.''

West Germany's Chancellor Helmut Kohl told a special Parliament session in Bonn: ''We feel sorrow for the unspeakable suffering which was caused to human beings and nations in the name of the Germans and by the hand of the Germans.''

''We mourn for the many innocent victims from within our own people,'' Kohl added.

As he spoke, a group of young Poles sat in the visitors' gallery. The group had been invited as a sign of reconciliation between West Germany and Poland, which suffered more than any other country from the Nazi atrocities.

There still are nagging questions over West Germany's relationship with Poland. Kohl has been under pressure from the opposition Social Democratic Party to visit Poland, as he has promised to do, and provide more financial aid to Warsaw.

''By delaying his visit, the chancellor is wasting good chances to give a clear expression to the reconciliation process between Poles and Germans,'' party leader Hans-Jochen Vogel said Thursday.

The Communist Party daily in Czechoslovakia, Rude Pravo, called the fighting that spread to all corners of the globe ''mankind's most terrible war.''

In Communist East Berlin, Foreign Minister Oskar Fischer called today a day of ''recollection and sorrow'' during a speech to the 500-member People's Chamber.

Fischer also repeated the commitment ''to do everything in our power to insure that war and fascism never again threaten our lives and the lives of our children.''

Corriere della Sera called Hitler's Blitkrieg ''the technology of a new Genghis Khan,'' the dreaded Mongol conqueror of central Asia.

It noted that Hitler had the support of the ''German masses,'' also pointing out that European political clout plunged after World War II.

Some of the most closely watched events were scheduled in Poland.

President Wojciech Jaruzelski was to speak at Westerplatte on the Baltic coast, where the first shots were fired.

''We will pay homage to all victims of the war, we will pay homage to its heroes and we will express the will to live in peace,'' said Wlodzimierz Lozinski, a spokesman for Jaruzelski.

American conductor Leonard Bernstein was to lead an internationally televised memorial concert in Warsaw, and Pope John Paul II was to address fellow Poles in Warsaw by a TV hookup.

But an event to bring together members of the world's dominant religions to pray for peace appeared likely to be marred by a boycott by Poland's only rabbi.

Rabbi Menachem Joskowicz said he would stay away because the Roman Catholic Church has not removed a convent from the Auschwitz concentration camp that many consider offensive to the memory of the 2.5 million Jews killed there.

Fifty years after the outbreak of World War II, there are still many unresolved issues traceable to Adolf Hitler's dictatorship.

They include the role of secret protocols in the 1939 non-aggression pact between Nazi Germany and the Soviet Union.

The agreement allowed the Soviets to take over the Baltic republics of Estonia, Latvia and Lithuania, and Western accounts say the pact paved the way for the start of World War II.

Recent Soviet reforms have emboldened residents of the Baltics, now the site of a growing independence movement.

The Kremlin on Thursday called World War II ''the most horrible and destructive of all wars.'' The commentary from the official Soviet news agency Tass then quickly lept to how the ''lessons of the past'' should lead the West to agreeing with Moscow on arms control issues.

In Bonn, ultra-conservative Finance Minister Theo Waigel said he did not deny ''one iota of German guilt'' for the war. But he added that ''a one-sided view of history with the conclusion that only the Germans are burdened with guilt would be unbearable and would lead to dangerous condemnations.''

Ultra-conservatives have long asserted that Soviet dictator Josef Stalin also shares some of the blame for the outbreak of the war.