"Today we summoned the charge d'affaires of the embassy," Norwegian foreign affairs ministry spokesman Kjetil Elsebutangen told AFP on Tuesday.
"We informed him that their diplomat's activity was incompatible with his diplomatic status and so we asked that he leave Norway," Elsebutangen said, specifying that he leave "quickly."
Norway's intelligence agency PST on Tuesday announced the arrest of a 38-year-old Sudanese man suspected of covertly gathering information on Sudanese refugees in Norway and transmitting it to someone at the Oslo embassy.
They did not specify the nature of the information gathered.
A spokesman for the embassy could not be immediately reached for comment.