FRANKFURT, Dec. 22 — In a sign of how badly German-Polish relations have frayed in recent months, a long-shot lawsuit by an obscure German claims group has prompted Poland to call into question a treaty meant to settle forever the borders between the countries.
The Polish foreign minister, Anna Fotyga, raised doubts about the treaty in a radio interview last Tuesday, a week after a group representing Germans expelled from present-day Poland after World War II filed suit at the European Court of Human Rights, seeking restitution of their property.
Though Ms. Fotyga has since backed away from suggestions that the treaty be renegotiated, she said Poland would push for a “legal solution” that “will respect the truth and the historical responsibility.”
In a statement issued Thursday, she condemned the German claims as “an attempt at reversing moral responsibility for the effects of World War II, which began with the German attack on Poland, and caused irreparable losses and sufferings to the Polish state and nation.”
Germans and Poles have squabbled over a lot of things in the past year, not least a new gas pipeline that Germany and Russia are building under the Baltic Sea, bypassing Poland. But the dispute this week was a reminder of how much of the ill will still hinges on their tragic shared history.
Germany brushed aside the need to renegotiate the 16-year-old treaty signed by Berlin and Warsaw after the fall of Communism. The treaty confirmed the post-World War II borders between the countries and foreclosed any claims by the German state on territory lost to Poland after the war.
The trouble is, the treaty did not deal with claims made by individuals. These new claims have reopened old wounds in Poland, where some people accuse Germans of trying to create a moral equivalence between the suffering of Germans and the suffering they inflicted on others.
The German government said it did not support the claims of the group, known as the Prussian Trust, but it also did not plan to impede them, since displaced Germans are an influential constituency here.
After the end of World War II, more than 12 million Germans were expelled from territories that are now part of Poland and other Eastern European countries. The Federation of Expellees, the main lobbying group for these people, has kept the issue alive in Germany, sponsoring an exhibit in Berlin last summer that also provoked outrage on the part of Polish leaders.
But even the federation has kept its distance from the Prussian Trust, which filed 22 claims with the Court of Human Rights in Strasbourg, France. Critics here said the group — which is small and consists largely of people who were expelled from the former Silesia — had reactionary tendencies.
Rudi Pawelka, a retired policeman who is the director of the Prussian Trust, said its goal was both symbolic and concrete. “We want the injustice of our expulsion to be recognized, and for there to be compensation,” he said in an interview. “And there the question of property ownership becomes relevant.”
Mr. Pawelka said the Prussian Trust chose to file claims with the Court of Human Rights because other displaced groups had successfully pressed their cases there. Poland, as a member of the European Union, would also be subject to any decision handed down by the court, he said.
German officials said the lawsuit was hopeless, and would only antagonize Polish officials — a point that seemed indisputable, given the statements by the foreign minister and the twin brothers who govern Poland, President Lech Kaczynski and Prime Minister Jaroslaw Kaczynski.
Some analysts said there was little that Germany could do but try to stay above the fray. The Kaczynski brothers, they said, were exploiting anti-German sentiment to fuel a new wave of Polish nationalism.
The government of Chancellor Angela Merkel has tried to support Poland in other ways, including its running conflict with Russia over Moscow’s ban on Polish meat products. That ban has led Poland to delay a broader partnership agreement between Russia and Europe.
Some experts on German-Polish relations said the vitriol of Poland’s leaders masked what was a generally healthy relationship on other levels. Trade between Germany and Poland is busy, and there are many exchanges between academics, students, and legislative officials.