Experts fear that theft damage to Edvard Munch’s painting “The Scream,” one of the world’s most famous images, may be too extensive to completely repair, according to a report released Friday.

The painting and another Munch masterpiece, “Madonna” were recovered by police in August, two years after they were stolen from Oslo’s Munch Museum by masked gunmen in a brazen daylight heist on August 22, 2004. Police have refused to say how they recovered the artworks or where they had been for the two years.

After extensive study, museum experts are turning over a 200-page assessment to Oslo police, which, among other things, expresses concern about moisture damage to a swath of “The Scream.”

“Water has been absorbed by one corner of the paper board, and there is abrasion damage on the lower part of the painting,” museum curator Ingebjoerg Ydstie told the TV-2 network. “We have a large swath that is very visible.”

She said the museum is still assessing what to do about the damage, and if it can be fixed, but that no decision had been made.

“There are types of damage we can’t do anything about,” museum restoration expert Anne Milnes told TV-2.

“The Scream” is probably the best known of Munch’s emotionally charged works and was a major influence on the Expressionist movement.

In four versions of the painting, a waiflike figure is apparently screaming or hearing a scream. The image has become a modern icon of human anxiety.

Museum spokeswoman Jorunn Christoffersen said yesterday that the museum would not comment further until after the report has been released, but he referred to a statement posted on the city-owned museum’s Web site.

It said experts are still trying to determine what kind of liquid caused the moisture damage in the lower left corner of “The Scream.”

“When one has further knowledge of the chemical composition one will know whether the damage is going to be stable, or whether one may risk the development of further future damage,” the statement said.

It also said there are ethical limits in the art world to how extensively a painting can be restored, and that any effort would be cautious because of the possible long-term impact of modern pigments and binding agents on the painting.

It was not clear how long it would take before “The Scream” could again be exhibited, and repairs to “Madonna” were expected to take even longer, the statement said.

“The painting will be cleaned, the threads in the tears will be joined one by one, and tiny, loose flakes of paint will be carefully fastened to the canvas with the help of a microscope,” it said.

“The Scream” and “Madonna” were part of Munch’s “Frieze of Life” series, in which sickness, death, anxiety, and love are central themes. He died in 1944 at the age of 80.