Otto Lauri Mikael Hjelt (4 September 1900 TuusulaOtavan Iso tietosanakirja, osa 3, palsta 792. Helsinki: Otava, 1962. −3 October 1972Mitä Missä Milloin, Kansalaisen vuosikirja 1974, s. 84. Helsinki: Otava, 1973.) was a Finnish diplomat, a master of philosophy.
Hjelt was employed by the Ministry for Foreign Affairs in 1924–1932 and again in 1939. He served as the division chief in 1944–1946 and as the head of the newspaper office in 1946–1949. Between 1949 and 1951, he was the Consul General of Finland in Gothenburg and in 1951–1957 he served as a Chancellor in Budapest. Hjelt was Ambassador to Brussels in 1957–1959; Ambassador of Foreign Affairs, 1959–1961; and Ambassador to Madrid 1961–1966.Facta2001, WSOY 1981, 6. osa, palsta 113Yrjö Blomstedt ja Matti Klinge (toim.): Paasikiven päiväkirjat, osa 2, s. 581. Porvoo-Helsinki: WSOY, 1986.
Hjelt's father was Arthur Hjelt.
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