The management at the Bruecke museum said they doubted the paintings could be sold on the art market because they were well known.

Stolen works include:

Ernst Kirchner's Tiergarten Berlin (1912) Emil Nolde's Herr Sch. (1915) Max Pechstein's Junges Maedchen (1908)

Police said the thieves got in through a back window after disconnecting the alarm.

Correspondents say the gallery houses one of the most important collections of expressionist art - a style that emerged largely in Germany in the early 20th Century.

'Degenerate art'

Bruecke - German for Bridge - was the name of the northern school of German Expressionism, a revolutionary artistic movement that flourished around the time of the World War II, promoting a subjective, emotional, angular art.

The group's works were banned as "degenerate art" by the Nazis after they took power in 1933.

The gallery in south-west Berlin, which was opened in 1967, has more than 400 paintings, drawings, watercolours and sculptures.