Two thieves walked into the Munch Museum on a Sunday afternoon, took the paintings off the wall and sped away.
The museum will remain closed while workers install new security equipment, Aftenposten reported Tuesday.
"We're waiting now for a security report from Den Norske Veritas," said museum leader Gunnar Sorensen. "That won't come until police complete their own risk evaluations."
Police said there has been no arrests in the case.