An unknown painting by Edvard Munch has been found hidden behind another canvas. The picture, found in the Kunsthalle, the main art museum in the northern German city of Bremen, shows three masklike faces looking down toward a naked, seated girl.

Restorers discovered it on a second canvas behind the museum's only Munch work, "The Dead Mother," director Wulf Herzogenrath said Friday.

The museum has christened the find "Girl and Three Men's Heads" and dated it 1898.

Herzogenrath said the picture was a boon for an art world still smarting from the theft of a version of Munch's famous "The Scream" and another picture from a museum in Oslo in 2004. Neither painting, worth tens of millions of dollars each, has been recovered.

Herzogenrath said the newly revealed work, which had remained undetected for more than 100 years, was "priceless."

The museum said that although the painting is unsigned, experts were sure it was Munch's and that it was produced days before the picture that concealed it.

Barbara Nierhoff, a German art historian, said the Norwegian painter and graphic artist, who worked in Germany as well as his home country, may have laid the second canvas on top simply because he didn't have a spare frame.

Museum director Wulf Herzogenrath and art historian Barbara Nierhoff show off Munch's newly discovered "Girl and Three Men's Heads."