Stolen works include:

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

Four men and one woman have been arrested in connection with the theft from the Bruecke museum.

The thieves had disconnected the alarm and smashed a rear window.

Six of the paintings were by Erich Heckel, and one each by Emil Nolde, Ernst Ludwig Kirchner and Max Pechstein. Most were painted between 1908 and 1920.

Eight of them were undamaged, but the Pechstein painting - Young Girl, painted in 1908 - had been slashed.

Nazi ban

The museum houses one of the most important collections of expressionist art, a style that emerged largely in Germany in the early 20th Century.

Bruecke - German for Bridge - was the name of a group of German painters whose founders in 1905 included Kirchner and Heckel.

Often associated with the freewheeling artistic life of 1920s Germany, the group's works were banned as "degenerate art" by the Nazis after they took power in 1933.

The Berlin museum, which opened in 1967, has more than 400 paintings as well as drawings, watercolours and sculptures.