The museum says it has increased security for the Scream and Madonna - Revisited exhibition, which will run until 26 September.

Mette Havrevold, head of Oslo city’s art conservation department, said the process of restoring the paintings had been a meticulous one.

“It was a challenge because we didn’t know anything about what these two paintings had been through,” she said.

“There were a lot of unknowns, in particular about where the humidity stain [in the bottom corner] came from.”

She said that, as she and her team were not certain they could repair the stain, it would remain because “it would be stupid to do something that would worsen the damage”.

Ripped canvas

Unveiling the paintings to reporters on Wednesday, museum chief Ingebjoerg Ydstie said it was now thought The Scream had been painted in 1910 - not in 1893 as was previously thought.

“Written sources, combined with style studies and, to a certain extent, technical observations made during the restoration of the painting, point to a more recent dating,” she added.

The theft and restoration of Edvard Munch’s most famous painting

The Scream and Madonna were stolen by two armed men who threatened a member of staff before ripping the paintings off the wall.

It is believed they later ripped the paintings out of their frames because they thought they could contain tracking devices.

The Madonna painting suffered worse damage than The Scream, including a ripped canvas.

Madonna, shown as a nude woman with long, dark hair, will undergo further restoration when the exhibition ends.

Three men were jailed last April for the robbery.

But one, Bjoern Hoen, had his conviction overturned by the Norwegian Supreme Court in January because of procedural lapses.

The Scream - one of the world’s most recognisable images - and Madonna were part of Munch’s Frieze of Life series in which sickness, death, anxiety and love were central themes. The artist was a major influence in the modern expressionist movement and died in 1944 at the age of 80.