Karsten Ludvig Sølvberg (19 January 1905 – 1976[1]) was a Norwegian communist, trade unionist and agent during the Second World War.
Before the Second World War he was a trade unionist and member of the Communist Party. He was a telegraph clerk by occupation.[2] His union was Norwegian: Norsk Telegrafforbund, and he edited the union's magazine Norwegian: Telegrafmannen.[3]
During the occupation of Norway by Nazi Germany, the Nazis merged his union with others to form the Norwegian: Forbundet for Offentlige Yrker. Sølvberg was a union secretary.[4] He was initially a member of the resistance movement, and was arrested in October 1942 by account of "illegal activity".[2] He was incarcerated at Norwegian: [[Møllergata 19]] from 27 October 42, and also at Victoria Terrasse. He was released on 16 April 1943.[5] He had then been subject to torture. He was pressured to denounce his communist adherence, and to become a Nazi agent with the codename S 71.[2] He is best known for unveiling the Communist Party organizational centres in 1942, which had been established in secrecy in Vikersund and Hemsedal. Sølvberg supposedly escorted Gestapo officers to both hideouts.[2] The underground Communist Party leaders Arne Gauslaa and Ottar Lie were surprised there; Gauslaa and another person were shot to death while Lie was arrested and tortured.[6] His agent practice was unveiled when Georg Angerer defected to Sweden.[4]
After the war Sølvberg was not reinstated in his job, nor in his trade union post.[7] He was however acquitted of treason by Oslo City Court in 1949, when tried as a part of legal purge in Norway after World War II.[2]