Yes, it is mandatory for foreign pilots.
3rd. part liability insurance, NOK 5.000.000,-
Norwegian pilots have mandatory accident insurance. This is not mandatory for foreign pilots.
If you are a pilot visiting competitions, the 3rd. part liability insurance are covered by the Norwegian Aero Club. If you visit Norway when not participating in a competition, you can become a member of our organisation. Then the 3rd. party liability insurance is included in the membership. Both these things require a valid pilot licence.