From 1972 to 1973 he was a member of Korvald's Cabinet as a State Secretary in the Ministry of Foreign Affairs. He represented the Centre Party and was also a member of Bærummunicipal council and Akershuscounty council. He has thus been one of the very few diplomats to hold an elected office in local politics in Norway.[2]
Svennevig was a member of the Defence Commission from 1974 to 1978. He was then the Norwegian ambassador to Iran from 1979 to 1982, and doubled as ambassador to Pakistan. Here, his tenure coincided with the Iranian hostage crisis. Then, after a period as a deputy under-secretary of state in the Ministry of Foreign Affairs and the Ministry of Development Cooperation. He was the Norwegian ambassador to Poland from 1986 to 1991. He was then the Norwegian ambassador to Hungary from 1991 to 1994, doubling as ambassador to Croatia.[2]