The Museum of Modern Art and the Solomon R. Guggenheim Foundation asked a court yesterday to declare them the rightful owners of two Picasso paintings that a Jewish scholar claims were the rightful property of a relative persecuted in Nazi Germany.

The two institutions said they took the step to fend off an expected lawsuit from Julius H. Schoeps, a German who has been waging a legal fight to recover artwork and property once owned by his great uncle.

Schoeps demanded on Nov. 1 that the museums hand over both works, "Boy Leading a Horse," which is in MoMA's collection, and "Le Moulin de la Galette," in the Guggenheim's collection.

MoMA director Glenn D. Lowry and Guggenheim Foundation director Thomas Krens said in a joint statement they are confident the paintings were not obtained under Nazi duress.

"The Museum of Modern Art and the Guggenheim Museum take the issue of restitution very seriously," they said. "Evidence from our extensive research makes clear the museums' ownership of these works and also makes clear that Mr. Schoeps has no basis for his claim."

Schoeps' lawyer, John J. Byrne, declined to comment on the museums' suit, filed in US District Court in Manhattan.

Both paintings were originally owned by Paul von Mendelssohn-Bartholdy, an aristocratic German banker and descendent of composer Felix Mendelssohn. Mendelssohn-Bartholdy died in 1935, two years after Adolf Hitler came to power.

At the time of his death, Mendelssohn-Bartholdy had been engaged in a series of maneuvers that Schoeps said were intended to protect his estate and an incredible art collection that also included nine paintings by Vincent van Gogh.

The family sold the two paintings, now owned by the museums, in 1934 or 1935 to Jewish art dealer Justin Thannhauser, who himself fled Germany and spent much of the war in Switzerland. Thannhauser kept "Le Moulin de la Galette" until 1963, when he gave it to the Solomon R. Guggenheim Museum. He sold "Boy Leading a Horse" to former MoMA chairman William Paley in 1936.

In a recent lawsuit involving a third Picasso, Schoeps argued that his great uncle only parted with the paintings because he expected his estate to be plundered by the Nazis.

Schoeps is the director of the Moses Mendelssohn Center for European-Jewish Studies at the University of Potsdam in Germany.

Over the years, he has also battled to recover the family's estate in Germany.