Tanev was born in Gevgelija, in the Salonica Vilayet of the Ottoman Empire (present-day Republic of Macedonia) and joined the Bulgarian Communist Party in 1919. After the failure of the September Uprising of 1923 he fled to the Kingdom of Yugoslavia, then moved between Communist Russia and secret missions in Bulgaria.
In 1933 Tanev was in Germany working for the Comintern under Georgi Dimitrov. On 9 March 1933 Tanev, Dimitrov and Blagoy Popov, along with others were arrested and charged with complicity in the Reichstag fire. All three were acquitted.
Tanev was acclaimed as a hero on his return to Russia, but was forced into self-denunciation later in the 1930s. The Bulgarian Communist Party ordered him to carry out a mission in Bulgaria in 1941, where he was killed later in that year.
- Frederick B. Chary (2007). "4: Boris III, Tsar of the Bulgarians". In Bernd Jürgen Fischer (ed.). Balkan Strongmen: Dictators and Authoritarian Rulers of South Eastern Europe. Purdue University Press. ISBN 9781557534552. Retrieved 10 September 2013.
- Milorad M. Drachkovitch (1986). Biographical Dictionary of the Comintern. Hoover Press. ISBN 9780817984038. Retrieved 10 September 2013.