German officials have signaled that they will appeal a decision by a U.S. judge in a case involving art allegedly looted by the Nazis.

The judge ruled that the heirs of Nazi-era Jewish art dealers can sue Germany in an American court over an alleged violation of international law.

The case involves medieval relics valued at more than $250 million. The heirs of the art dealers say their relatives were forced to sell the relics in 1935 in a coerced transaction.

Germany argues that the sale was voluntary and tried to get the case dismissed under a law that exempts foreign states from being sued in the U.S.

Attorneys for Germany and the Prussian Cultural Heritage Foundation filed a notice of appeal Friday in U.S. District Court in Washington.