The Russian Foreign Ministry on Friday said it had expelled a senior Norwegian diplomat in retaliation after Oslo expelled a Russian diplomat following the arrest of a suspected spy.
The Russian ministry said that "as a retaliatory measure" a senior diplomat at the Norwegian embassy was declared persona non grata and must leave within three days.
Russia accused Norway of taking a "destructive course" that would "inevitably negatively affect the atmosphere of bilateral relations."
Norwegian foreign ministry spokeswoman Guri Solberg called the diplomat's expulsion "totally without foundation" in a statement sent to AFP. Norway named the diplomat as Jan Flaete.
It came after Norway announced the expulsion of a Russian diplomat on Aug. 19, days after arresting a Norwegian man suspected of passing sensitive information to Moscow.
Oslo accused the Russian diplomat, who worked in the trade section, of acts "not compatible with his status as a diplomat."
The diplomat was with the Norwegian man at the time of his arrest at an Oslo restaurant.
The Norwegian, identified by court documents as Harsharn Singh Tathgar, risks up to 15 years in prison if found guilty of espionage.
He worked for DNV GL, a company that provides certification for oil and gas industries.
The 50-year-old man told investigators he had handed over information in exchange for "not insignificant sums in cash," but insisted the information was not harmful to Norway's interests.
In recent decades several spy cases have marred ties between NATO member Norway and Russia, which share a border in the Arctic Circle.