BOSTON—The Museum of Fine Arts, Boston has filed a federal lawsuit to retain ownership of Oskar Kokoschka's 1913 oil Two Nudes (Lovers), sold during the Nazi occupation of Austria, the Associated Press reports.

Attorneys for Claudia Seger-Thomschitz say Oskar Reichel, a Jewish physician who ran an art gallery in Vienna, sold the painting under duress in 1939. The MFA says the painting, which changed hands several times before being donated to the museum in 1972, was sold voluntarily to another Jew.

Lawyers for Seger-Thomschitz, designated by one of Reichel's sons as his "select niece and designated heiress," first asked the MFA in March to return the painting, of Kokoschka with Alma Mahler, composer Gustav Mahler's wife and Kokoschka's mistress. The lawyers claim Reichel was forced to close his medical practice and sell his gallery to survive.

Museum curator George Shackelford said the MFA has returned works, including paintings taken during World War II, that were determined to have been taken from their rightful owners. Ori Soltes, co-founder of the Holocaust Art Restitution Project in Washington, D.C., told the Boston Globe he was impressed by the MFA's research.