Bertone will be replaced by archbishop Pietro Parolin, the Vatican's representative in Venezuela, the Italian news agency ANSA reported, citing a story in the daily Corriere della Sera.
An announcement is expected Sunday.
Benedict XVI appointed Bertone secretary of state.
He will remain president of the Commission of Cardinals until December when the Council of Europe is expected to release a report on anti-money laundering procedures for the Vatican Bank.
2014: The Year in Music [PHOTOS]