The heads of state of Germany and Poland agreed Thursday that a "calm discussion" was necessary to address the question of reparations from World War II, the Polish presidency said.
Polish President Andrzej Duda and his German counterpart b met in Malta on the sidelines of a conference of 13 EU members.
"The presidents discussed the political and legal contexts of the question of reparations," said Duda's chief of staff Krzysztof Szczerski, as quoted by Poland's PAP news agency.
"They said it would require a calm discussion and that, independently of how the situation evolves, they would do everything to preserve the rich gains in Polish-German relations."
The question of whether Germany owes Poland war reparations -- for years considered as settled -- was brought up on July 28 by Jaroslaw Kaczynski, leader of Poland's ruling rightwing Law and Justice (PiS) party.
Last week, Prime Minister Beata Szydlo said Poland "has the right" to ask for reparations.
But German government spokesman Steffen Seibert dismissed Warsaw's threat to demand new talks, saying the issue had already been settled when "Poland made a binding decision in August 1953... to relinquish demands for further war reparations."
Signed in 1953
Signed by Warsaw's communist authorities, the 1953 agreement on reparations renounced further claims against Germany.
But the PiS government disputes the validity of the post-war deal, saying it was made under the diktat of the Soviet Union.
Poland's foreign and interior ministers have estimated potential reparations reaching as high as $1 trillion (830 billion euros).
During the war, Poland suffered the brunt of the two-front attack by Nazi Germany and the Soviet Union.
Six million Polish citizens, including about three million of Jewish origin, were killed under the Nazi occupation of 1939-45, and Warsaw was virtually razed.
According to a survey published last month, 51 percent of Poles oppose any reparation claims against Germany, while 24 percent are in favour.
Poland's powerful Roman Catholic church warned last week that "poor decisions" by the country's rightwing leaders could "undermine" ties with Germany.
The talk of reparations comes as the PiS government is under fire both at home and abroad over a slew of reforms that critics say erode democratic standards and the rule of law.