The director bought Norman Rockwell's Russian Schoolroom 18 years ago from a legitimite dealer, unaware it had been stolen.

His staff realised what had happened last week when they recognised the painting on a theft notice issued by the FBI.

The bureau said it was stolen in 1973 from an exhibition in Missouri and was worth an estimated $700,000 (¡ê360,000).

It said Spielberg would hold on to the painting, which features a group of children in a classroom with a bust of Vladimir Lenin, until its "disposition" could be decided.