Warsaw/Berlin - As Polish and German leaders commemorate the events which caused the start of World War II on September 1, 1939, they can look back on 70 years of chequered history.

Historical events dating back to Nazi Germany's attack on Poland still haunt the relationship between the two countries, exemplified by a spat in recent years over EU voting reform.

Poland fought hard against EU voting reforms proposed under the Lisbon treaty, arguing that the new system gave too much clout to the EU's bigger states like Germany.

Poland's then governing twins, President Lech and Prime Minister Jaroslaw Kaczynski, argued at the time that Poland's population would have been bigger had it not been depleted by Nazi German forces during World War II.

A last-minute compromise was reached, but Polish recriminations continued after the summit, with a conservative magazine publishing an unflattering caricature of German Chancellor Angela Merkel.

The cover of Wprosta showed the chancellor breast-feeding the Kaczynski twins under the title "Stepmother of Europe," prompting outrage in Germany.

Jaroslaw Kaczynski subsequently compared modern day Germany to the era that brought Adolf Hitler to power, while Germany's Bild newspaper referred to the twins as "poison dwarves."

More recently, controversy came to a head over a planned museum in Berlin about German refugees who were expelled or fled Poland and other East European countries after World War II.

Poland was furious when Erika Steinbach, a federal deputy for German Chancellor Angela Merkel's Christian Democratic Union (CDU), was up for nomination to the museum's board.

Polish fears were that Steinbach, who was born in Poland two years before the end of World War II, would demonise Poles and show a pro- German bias by portraying Germans as the war's victims.

Poles also charge that Steinbach's parents were aggressors because they moved to the country after the Nazi takeover.

Germany eventually bowed to Poland's fierce criticism and withdrew Steinbach's nomination in March.

Another sore spot is the planned Baltic Sea gas pipeline that would carry natural gas from Russia to Germany, bypassing Poland.

The Nord Stream pipeline is seen by Polish critics as Moscow's attempt to snub Warsaw, as it could be used to threaten Polish gas supplies without endangering gas flow to Western Europe.

Foreign Minister Radoslaw Sikorski lashed out at the project in May 2006 by comparing it to the 1939 Molotov-Ribbentrop pact signed behind Warsaw's back, which divided Poland between Soviets and Nazis.

Poland has been assuaged in recent years by German efforts to help Poland enter the European Union and its diplomatic gestures of regret for World War II.

However, Germany has cast aspersions on its eastern neighbour, expressing fears in 2007 that opening its Schengen borders to Poland would lead to a wave of crime in the border regions.

On the contrary, a year later crime had fallen in areas bordering Poland. Nevertheless, Poland remains sensitive to its portrayal in German media and pop culture.

German daily Die Welt is being taken to court by a Pole after the newspaper used the expression "Polish concentration camp," to describe Nazi camps in occupied Poland.

The Pole Zbigniew Osewski said he's suing because the comment is offensive, and personally hurtful as Osewski's grandfather died in a Nazi prison, Polish Radio reported.

Elderly Poles who lived through World War II may find it hardest to shake off the bad stereotypes.

"For us, Germany for a long time will be associated with World War II. But when it comes to work for unity, it's going well," said Waldemar Czachur, coordinator of German projects at the Centre for International Relations, a Warsaw think-tank.

"On one hand, it's easy for Poles to activate the stereotype of the evil German. It's a product of a certain upbringing," Czachur said.

"In a couple years, I think it will be harder to mobilize so many Poles against the Germans, because Poles are seeing German politics is not anti-Polish," he said.

"(Germany) is opening up more to the Polish voice, and appreciating Poland's role," Czachur added. (dpa)