Oslo  - On the eve of a special exhibition showing the painstaking work to restore two paintings by Norwegian artist Edvard Munch stolen in 2004, the Munch Museum said Thursday that one of the works, The Scream, has been redated.

Until recently, the Munch Museum version of The Scream was dated to 1893, the year after Munch described a deeply unsettling experience while walking with two friends according to an entry in his journal.

The new date was to be revealed next week, museum spokeswoman Jorun Christoffersen told news agency NTB, saying the new assessment was made during the extensive restoration work to repair damages caused in connection with the 2004 theft.

The two stolen masterpieces were recovered in August 2006.

The exhibition entitled Scream and Madonna - Revisited opens May 23 and runs through September 28.

Restoration work has failed to remove "a stain in the lower left corner" of The Scream while some retouching remained to be done on The Madonna, the museum said.

"But the artistic value of the paintings has not been reduced," Munch Museum chief curator Ingebjorg Ydstie said.

Munch, who lived from 1863 to 1944, is considered one of Europe's most important expressionist artists. He made several versions of the two recovered works. (dpa)