Switzerland opened a consulate in Oslo in 1847 (which was upgraded to a consulate general in 1921). Norway established a consulate general in Zurich in 1906. In 1918, the Norwegian ambassador in Rome was accredited to Bern and the Swiss representative in Stockholm was accredited to Oslo. The legations that were opened in Bern and Oslo after the Second World War were upgraded to the status of embassy in 1955 and 1957 respectively.
Since 1951, the Swiss ambassador in Oslo has also been accredited to Iceland. In 2006, King Harald and Queen Sonja made a state visit to Switzerland. Doris Leuthard, the then President of the Swiss Confederation, was invited on a state visit to Oslo in 2010.
Norway, Historical Dictionary of Switzerland (de, fr, it)